Manage tile layers

Owners of tile layers and organization administrators can manage settings and content for the layers. Management options vary depending on whether the layer contains raster tiles or vector tiles and whether the layer has an associated feature layer.

Tip:

Layers that reference a cache dataset or that you publish from a package never have an associated feature layer.

The layer item is a tile layer or tile layer (hosted). Use the layer icon to identify whether it is a raster tile layer or vector tile layer.

The following table indicates what management options you have per layer type.

	Raster tile layers	Vector tile layers
Set the minimum and maximum scales at which the layer draws when added to a map (the visible range and resampling).	Yes	No
Configure the layer for use in offline maps and apps.	Yes	Yes
Choose at which scales cached tiles are built.	Yes	No
Replace the contents of the layer using a second layer.	Yes This is supported for layers that don't have an associated feature layer.	Yes This is supported for layers that don't have an associated feature layer.
Rebuild the layer cache to receive updates from the associated feature layer.	Yes This is supported if you published the layer from a hosted feature layer or from a service definition file.	Yes This is supported if the vector tile layer has an associated hosted feature layer or map image layer.

Manage raster tile layer settings

You can manage minimum and maximum scales (visible range or level of detail) and the offline mode on raster tile layers.

When you publish a hosted tile layer from a hosted feature layer or hosted feature layer view, the tile layer inherits the visible range of the source layer. You cannot build tiles for areas that fall outside that inherited visible range.

Visible range and resampling for raster tile layers

As the layer owner or organization administrator, you can define the minimum and maximum scales at which the layer will draw. This is the visible range for the layer. When a user zooms past the minimum or maximum scale, the layer content will not draw.

When you publish a tile layer, you may choose to not generate tile caches for sparsely visited areas or detailed scales to save disk space and reduce the time taken to generate the cache. However, when using the layer, a user can pan or zoom to areas within the visible range for which there are no cached tiles. When they do that, the client where the layer is being used (such as ArcGIS Pro or Map Viewer) will resample to render content in areas within the visible range where there are no cached tiles for the layer.

Resampling uses the existing tile cache to fill in the gaps in the areas where you have not generated tiles at that scale. The resampled content is based on the closest level of detail (tiles) available for the layer. This provides a smoother experience for users, but the output can be blurry, particularly when the level of detail being resampled is far from the source level of detail. For example, if the maximum scale where cached tiles are present in a specific area of the map is 1:5000, and a user zooms to 1:100 in that area, the resampled cache will likely lose clarity and accuracy.

If you find that users are regularly zooming past the minimum or maximum scale value you defined for the tile layer's visible range, increase the visible range and build the tiles at larger scales.

Configure raster tile layer settings

Follow these steps to build tiles, change the visible range, and manage the offline mode of a raster tile layer :

1. Sign in as the owner of the web layer, an administrator, or with an account that has privileges to update all members' items.
2. Open the tile layer's item page.
3. Click the Settings tab.
4. Scroll down to the layer's settings section.
5. Use the Visible Range slider to define the minimum and maximum scales at which the tile layer will be visible and the area in which tile caches can be built.

   Nothing will draw outside the visible range.

6. Click Tile Details to access the current status of existing cached tiles.
7. To build cached tiles for the layer, follow these steps:
   1. Click Build Tiles to build tiles for the layer.
   2. When the dialog box appears, check the boxes next to the levels (scales) at which you want to generate tiles.

      You must choose at least one level.

   3. When you finish choosing levels, click Create Tiles.
8. Optionally, check Allow this layer to be downloaded and used in an offline map to allow others to include the tile layer in a map that will be taken offline.

   You can only do this if you've created tiles for the data you want to take offline.

9. Click Save when you finish.

Replace a raster tile layer

If a hosted tile layer does not have an associated feature layer, you can update the tile layer's contents by replacing it with another tile layer that you published from ArcGIS Pro or from a tile package or service definition file. For raster tile layers that reference a cache dataset in a folder or cloud data store, you can replace it with another raster tile layer that references a cache dataset. This allows you to update the contents of a tile layer without deleting it. You must own both the existing and the replacement layer.

Tip:

If the hosted tile layer has an associated feature layer, you cannot replace the tile layer. You can identify whether the tile layer has an associated feature layer by checking the Details section of the tile layer's item page.

Replacing a tile layer provides the following benefits:

• Because the item ID and URL of your existing layer don't change, the web maps and apps that use your layer do not need to be updated to reference a new layer. Web maps and apps that use the current layer will continue to work after you replace the layer.
• Replacing the contents of the current layer does not generate new tile caches. Therefore, no one has to wait for the tile layer cache to be rebuilt.
• ArcGIS Enterprise creates an archive of the old content, which allows you to revert to this content if necessary.

Note:

Be sure you use the same tiling scheme for the replacement tile layer as you did for the current tile layer. This setting must match.

Follow these steps to replace an existing raster tile layer with another tile layer:

1. Sign in as the owner of the web layer, as an administrator of the organization, or with an account that has privileges to update all members' items.
2. Open the raster tile layer's item page.
3. Click Replace Layer.
4. Click Select layer.

   In the pane that appears, you can search, browse, filter, and sort available layers to find the replacement tile layer. You can also view the item details for each layer by clicking View details.

5. When you locate the tile layer you want to use, click Select.
6. Click Next to choose how to archive the current raster tiles. Choose one of the following options:
   • Archive the current layer—Use this option to maintain a snapshot of the current raster tile layer content as it existed prior to updating it. By default, the new layer's name consists of the current layer name with _archive_<current date and time> appended to it. To specify a different name, click the edit button and type a new one.
   • Use the replacement layer—Use this option if you don't need a new layer to store archived content. The replacement layer is retained for future updates.
7. To import an updated thumbnail, summary, description, and tags from the replacement layer, scroll down and enable Replace item information.

   The summary page shows your current raster tile layer, the layer that will replace the content in the current layer, and information related to the archive layer.

8. To use a different replacement layer, click Select replacement layer and choose a new layer.
9. Once you are satisfied with all the layers, click Replace to perform the replacement operation.

Manage vector tile layer settings

Follow these steps to manage the offline mode of a hosted vector tile layer :

1. Sign in as the owner of the web layer, as an administrator, or with an account that has privileges to update all members' items.
2. Open the vector tile layer's item page.
3. Click the Settings tab.
4. Scroll down to the layer settings section.
5. Check Allow this layer to be downloaded and used in an offline map to allow others to include the vector tile layer in offline apps.
6. Click Save.

Rebuild vector tile cache

If you published the hosted vector tile layer from a hosted feature layer or hosted feature layer view or you published the vector tile layer from ArcGIS Pro with an associated feature layer or map image layer, you can rebuild the vector tile cache to incorporate changes made in the feature layer. You can rebuild the cache immediately or define a schedule to update the cache on a regular basis.

Rebuild cache immediately

Follow these steps to start the rebuild of the vector tile layer cache from the layer item's settings.

1. Sign in to your organization as the vector tile layer owner or an organization administrator.
2. Open the item page for the vector tile layer, click the Settings tab, and scroll down to the tile layer section.
3. Click Rebuild Cache.

   The cache immediately begins rebuilding. When it completes, you can open the hosted vector tile layer in a map to confirm updates were brought in from the associated feature layer.

Schedule the cache to be rebuilt

You can define a schedule to rebuild the vector tile layer cache on a regular basis, and incorporate changes from the associated layer. This allows you to rebuild cache—which is a resource intensive task—at a time when fewer people are accessing the ArcGIS Enterprise machines or the vector tile layer.

When you configure tasks to rebuild the cache at regular intervals, consider how frequently the data is updated, and balance the resource burden placed on the ArcGIS Enterprise machines to rebuild the cache against your users' tolerance for out-of-date vector tile layer data.

Follow these steps to establish a schedule to rebuild vector tile layer cache:

1. Sign in to your organization as the vector tile layer owner or an organization administrator.
2. Open the item page for the vector tile layer, click the Settings tab, and scroll down to the tile layer section.
3. Click Schedule tasks to rebuild the cache to expand that section.
4. Click Add rebuild task.
5. Define the schedule for the task.
   1. Click Beginning On and choose the date on which the task will start running.
   2. To define the unit of time when the task will repeat, choose one of the options in the Repeat type drop-down menu.
   3. Use the Repeat interval drop-down menu to choose how often to rebuild.

      Keep in mind that it may take many minutes or hours to rebuild the vector tile layer cache, depending on its size. Do not schedule the rebuild task to run more frequently than each individual rebuild operation can complete.

   4. Use the Ending on drop-down menu to choose when the tasks will stop running.

      Options are as follows:

      • Never—The task will continue to run at the specified intervals until you edit, pause, or delete the task.
      • Date—When you choose Date, the End date field appears. Choose the date on which the tasks will stop running.
      • Count—To run the task a specific number of times, choose Count and use the up or down arrows to specify the number of times the task will run at the interval you specified.

   5. Click Create to implement the schedule.

Replace a hosted vector tile layer

Vector tile layers deliver map data as vector files and include one or more layers that are rendered on the client based on a style delivered with the layer. To update the content of a hosted vector tile layer that you published from a vector tile package or published from ArcGIS Pro without including a feature layer, or to update a vector tile layer that references a vector cache dataset, replace the vector tile layer with the content from a second layer.

The Replace Layer option allows you to replace a vector tile layer in your portal with content from a second vector tile layer. When you replace a vector tile layer, the content of the layer is replaced with the content of the second layer. Because the item ID and URL of your layer don't change, the maps and apps that use the layer do not need to be updated to reference a new layer.

To replace a vector tile layer, you must own the current vector tile layer and the replacement layer. Organization administrators can also replace vector tile layers, but both the replacement layer and the current layer must be owned by the same organization member.

Replacing the layer provides the following benefits:

• You can create a replacement layer and perform quality control testing on this replacement layer without impacting users of the current vector tile layer.
• If you defined multiple styles for the current vector tile layer, you can preview how each style will look with the replacement layer.
• Replacing the contents of the current layer does not generate new tiles. Therefore, no one has to wait for the tiles to be extracted and rebuilt. Maps and apps that use the current layer will continue to work as expected after you replace the layer's contents.
• You can archive the old content, which allows you to revert to this content if necessary.

Note:

Before you publish or package the replacement vector tile layer in ArcGIS Pro, be sure you use the same coordinate system and tiling scheme for the replacement vector tile layer as you did for the current vector tile layer. These settings must match.

See Changes in the replacement layer that can adversely affect the current layer for information on other configuration changes you should be aware of when generating a replacement layer in ArcGIS Pro.

When you replace the layer, you can either move the current layer's contents into a new layer or swap the contents of the current layer and the replacement layer, thereby using the existing replacement layer as an archive.

• If you want to archive the current vector tile layer's content each time you replace the layer, create an archive of the current layer. You can use any of the layers that contain archived content to revert to an older version of the content if necessary. To revert to the contents of an archive, use the Replace Layer option and select the specific layer that contains the archived content you want to put back in the current layer.

  Use this option if you intend to create multiple layers with archived content that reflect changes in the vector tile layer content over time. For example, if you perform quarterly updates, you can create archives such as 2020Q4 and 2020Q1, which creates an archive for each update.

• When you use the replacement layer as the archive, no separate layer is created for archived content. The content from the replacement layer moves into the current layer. The content from the current layer moves into the replacement layer. Use this option if you don't need a separate layer for archived content.

In addition to deciding how to archive, choose whether you want to update the following item information in the current production layer or import changes from the replacement layer: thumbnail, summary, description, and tags. By default, the information is not updated. To import information from the replacement layer, enable the Replace item information option.

1. Sign in as the owner of the web layer, as an administrator of the organization, or with an account that has privileges to update all members' items.
2. Open the vector tile layer's item page.
3. Click Replace Layer.
4. Click Select layer.

   In the pane that appears, you can search, browse, filter, and sort available layers to find your replacement tile layer. You can also view the item details for each layer by clicking View details.

5. When you locate the vector tile layer you want to use, click Select.

   If you see a warning message about incompatible styles, it means the style on the replacement layer is different than the style on the current layer. This difference can potentially break any other styles that reference the current layer. Similarly, if the tiling scheme of the replacement layer is different than that of the current layer, you'll see this message. If you do not want to use this replacement layer, click Change layer and choose a layer that does have a matching style. You can proceed with replacing the current layer with a layer that has different styles.

6. Click Next to choose how you want to archive the current vector tiles. Choose one of the following options:
   • Archive the current layer—Use this option if you want to maintain a snapshot of the current vector tile layer content as it existed prior to updating it. By default, the new layer's name consists of the current layer name with _archive_<current date_and_time> appended to it. To specify a different name, click the edit button and type a new name.
   • Use the replacement layer—Use this option if you don't need a new layer to store archived content, and you want to retain the replacement layer for future updates.
7. To import an updated thumbnail, summary, description, and tags from the replacement layer, scroll down and enable Replace item information.
8. Click Next to preview the styles associated with the replacement layer.

   Note:

   The option to preview styles is only available if you created other styles for the current layer in the vector tile style editor.

9. Use the Other styles drop-down menu to preview what each style will look like in the current layer once you've updated it with the content in the replacement layer. Use the search and swipe element in the preview window to compare the replacement and current layers.
10. If you want to proceed, click Next. If you do not, click Cancel.

    The summary page shows your current vector tile layer, the layer that will replace the content in the current layer, and the archive option you chose.

11. If the replacement layer is not completely compatible, click Select replacement layer and choose a new layer.
12. To change archive options, click Choose archive option and change your settings.
13. When you are satisfied with your layer and archive choices, click Replace to perform the replacement operation.

Common workflows for replacing a vector tile layer

There are a few different ways to make use of the Replace Layer option to replace the contents of vector tile layers. Because the terms current layer and replacement layer are relative, it may help you to read some example workflows for replacing vector tile layer contents.

The next three sections describe workflows that make use of two or more vector tile layers to maintain vector tile data. These workflows use example layers to help you follow along with how content moves through each workflow. In all these examples, you have the current vector tile layer that people use in their maps and apps and at least one replacement vector tile layer. When you perform a similar workflow, you may have a different number of replacement layers or layers that contain archived content. You or other people who access the current vector tile layer may also have other styles defined for the layers.

Archive current content in a new layer

In this example scenario, you have a vector tile layer that stores service area boundaries. This is the production layer that people use in their maps. To update the contents of this layer, you publish a second vector tile layer that contains updated service area data. This is the replacement layer.

You also want to keep an archive of the content from the production vector tile layer each time you update it. That way, if you find an issue with the replacement content, you can revert the vector tile layer's content to the state it was in before you updated it. To allow for this, you'll choose to archive the existing content of the current vector tile layer in a new vector tile layer.

In the following example, you update your current vector tile layer, ServiceAreas, to reflect changes to service areas and attributes.

1. Publish a vector tile layer that contains updated data.

   This is the layer that you'll use to replace the content in the current vector tile layer.

   For example, several new customers were added to two of your service areas in September 2019, which altered the boundaries of those two areas. You update the source data to reflect the change in the areas and publish a vector tile layer named ServiceAreasUpdateSept. Because the boundary areas changed, you also configure a new thumbnail for this layer. You set the description, summary, and tags to be the same as the current layer, however, as there's no need to change those.

2. Open the item page of the ServiceAreas layer (the current layer) and replace its content with that of ServiceAreasUpdateSept (the replacement layer). Choose the Archive the current layer option to create a third vector tile layer to store the old content of the production vector tile layer. Specify a name for this layer that is meaningful to your organization.

   For example, the content of the production vector tile layer reflects district area data current to August 2019. Therefore, you name the new layer ServiceAreasAug2019_arch because it is an archive of the service area boundaries as they existed in August 2019.

3. Because you updated the thumbnail to reflect the change to the boundaries, enable Replace item information to update the thumbnail on the current vector tile layer with the one in the replacement layer.

   When you archive the current layer's contents, the replacement layer is deleted. Therefore, after you replace the current vector tile layer's contents for the first time in this specific example, you have the following two vector tile layers:

   • ServiceAreas—This is your production vector tile layer that now contains service area updates current to September 30, 2019.
   • ServiceAreasAug2019_arch—This vector tile layer contains the state of your service areas as of August 2019.

   The replacement vector tile layer (ServiceAreasUpdateSept) has been deleted.

In this example scenario, in October, one of your service representatives goes on extended leave, and you hire a temporary worker who starts work on October 7.
4. Update the service representative attribute information for that area and publish a replacement layer named ServiceAreasUpdateOct.
5. Replace the content of ServiceAreas with that of ServiceAreasUpdateOct and create a layer named ServiceAreasOct62019_arch to store archived content.

   At the end of this process for this specific example, you have the following vector tile layers:

   • ServiceAreas—This is your production vector tile layer that now contains service area updates current to October 7, 2019.
   • ServiceAreasOct62019_arch—This vector tile layer contains the state of your service areas as of October 6, 2019.
   • ServiceAreasAug2019_arch—This vector tile layer contains the state of your service areas as of August 2019.

There are no changes to the service areas for the rest of October. The service representative returns to work on November 4.
6. Because the service representative information was the only change made to the layer between October 6 and November 4, use the ServiceAreasOct62019_arch layer to return your production layer to the state it was in before the service representative went on leave.

   When you replace the contents of the ServiceAreas layer with ServiceAreasOct62019_arch, you can archive the state of the layer from October 7 to November 3 in a new layer, ServiceAreasOct7toNov32019_arch.

   You now have the following vector tile layers:

   • ServiceAreas—This is your production vector tile layer that contains service area updates current to November 4, 2019.
   • ServiceAreasAug2019_arch—This vector tile layer contains the state of your service areas as of August 2019.
   • ServiceAreasOct7toNov32019_arch—This vector tile layer contains the state of your service areas while you employed the temporary worker.

You continue to create layers that you'll use to replace content, update your current vector tile layer, and create layers to archive layer content as changes are required to your service areas. You can keep the layers that store archived content as long as needed and use them to revert to any previous update.

Keep the following in mind when you use this workflow:

• To help organize the layers that store archived content, create a folder specifically for these layers and move the layers into it.
• Because you create layers that archive older content in case you need to restore the production vector tile layer to an older state, and only you or an administrator can restore the data using these layers, there is likely no need for you to share them.
• The replacement layer is deleted. If you created multiple styles for the replacement layer, they will no longer function. You can delete them manually.

If your workflow requires you to maintain your replacement layer for future use—such as when you have styles you want to maintain on the replacement layer or you need to use the replacement layer in maps and apps for testing purposes—use one of the next two workflows instead.

Maintain the replacement layer

You can keep your replacement layer for testing or other uses. If you need to maintain the replacement layer, and you don't need to keep multiple layers that contain snapshots of the state of the current vector tile layer before each update, you can swap content between the current layer and the replacement layer. For example, you may want to keep your replacement layer if you want to use it to test updates before you push the changes into the current layer. This quality control workflow is summarized in this section.

To continue with the service area example, if you decide you don't need to archive content in new layers and, instead, you want to have a layer you can use for quality control testing, you can use the replacement layer for this testing. You can open maps and apps that contain the replacement layer to ensure that styles still function, the correct data shows up and at the correct extent, and the layer still functions in offline maps if required.

In this example, you would use the following three vector tile layers, two of which you keep and one you delete:

• ServiceAreas—This is the production vector tile layer that organization members use in their maps.
• ServiceAreasQC—You use this layer to review contents and styles before pushing updates into the ServiceAreas layer. This is the replacement layer, but you don't want to delete it because you've created web maps and apps that reference this layer as part of testing layer updates.
• ServiceAreaUpdates—Each time you update the source service area data, you publish a vector tile layer that contains the data updates. You use this layer to update the content in your quality control layer. After you replace the content in ServiceAreasQC with the content in ServiceAreaUpdates, you delete ServiceAreaUpdates.

A summary of this workflow is as follows:

1. Update the service area source data and publish the ServiceAreaUpdates vector tile layer.

   For example, after the boundary of two service areas changed as a result of new customers, you update the source data and publish the ServiceAreaUpdates vector tile layer.

2. Open the item page for ServiceAreasQC and replace its content with the content in ServiceAreaUpdates. Choose the Use the replacement layer as the archive option.

   In this step, ServiceAreasQC is considered the current layer and ServiceAreaUpdates is the replacement layer.

   This moves the contents from ServiceAreaUpdates into ServiceAreasQC and the current contents of ServiceAreasQC into ServiceAreaUpdates.

3. Test the updated ServiceAreasQC layer in the maps and apps you created for this purpose. Once you determine the updates do not cause any problems, update the content of the ServiceAreas layer with that of ServiceAreasQC. Choose Use the replacement layer as the archive again so the ServiceAreasQC layer is not deleted.

   In this step, ServiceAreas is the current layer and ServiceAreasQC is the replacement layer.

4. Now that you have finished the process of testing updates and updating the content in your production layer, delete the ServiceAreaUpdates layer from My content.

Repeat these steps whenever there are changes to the service area source data.

Keep the following in mind when you use this workflow:

• The replacement layer you use for testing (ServiceAreasQC in this example) contains the content of the current layer in the state it was in before you updated it. That means you can use this testing layer to restore the old content to the current layer if needed.
• If you need other people to test the updates before you replace the content of the current layer, share the replacement layer with a group that contains these members.

Maintain the replacement layer and archive content to a new layer

If you want a quality control layer and layers of archived content, you can use the two workflows described above in combination to update the current layer's content, maintain the replacement layer, and create layers to archive changes.

1. Complete steps 1 through 3 in the previous section.

   The first time you complete these steps for this example, you have the following vector tile layers:

   • ServiceAreas—This layer contains the latest updates.
   • ServiceAreasQC—This layer contains the contents from the ServiceAreas layer before you updated it. Therefore, it is temporarily an archive of the old ServiceAreas content.
   • ServiceAreaUpdates—This layer contains the contents from ServiceAreasQC before you replaced its contents.

2. Next, use the ServiceAreaUpdates layer to replace the contents of ServiceAreasQC a second time. This time, though, choose the Archive the current layer option to create a vector tile layer to archive the contents of ServiceAreasQC.

   In this scenario, ServiceAreasQC is the current layer and ServiceAreaUpdates is the replacement layer.

   This process results in the following:

   • A vector tile layer that serves as an archive of the old ServiceAreas content—Because ServiceAreasQC contained the archived ServiceAreas content, you've now moved that content into a separate vector tile layer. Name this layer appropriately to reflect its contents.
   • The ServiceAreasQC layer is restored to the state it was in before you replaced it with updated content from the ServiceAreaUpdates layer.
   • The ServiceAreaUpdates layer is deleted.

For example, if you use this workflow with the service area boundary updates from September 2019, ServiceAreas contains the September 2019 updates. The layer that stores the last batch of archived service area content contains service areas from August 2019, so you may have named this layer ServiceAreasAug2019_arch and moved it to your archive folder. ServiceAreasQC also contains the August 2019 contents.

When you complete this workflow again to propagate the October 7 edits from the source service area data to the ServiceAreas layer, you'll have the ServiceAreas layer with October 7 content, a layer of archived data that reflects the previous state of the service areas (ServiceAreasOct62019_arch), and the layer that contains contents archived from August 2019 (ServiceAreasAug2019_arch). ServiceAreasQC still contains the August contents as well.

When the service area representative returns from leave on November 4, you can use the ServiceAreasOct62019_arch layer to return your production layer to the state it was in before the service representative went on leave. Use the ServiceAreasOct62019_arch layer in place of the ServiceAreaUpdates layer in the steps listed in this section.

Keep the following in mind when you use this workflow:

• As with the first workflow, you can create a folder and move the layers that store archived content into it to help organize these layers.
• Because content you archive in separate layers is only needed to allow you to restore the production vector tile layer to an older state, and only you or an administrator can restore the data using these layers, there is likely no need for you to share these layers.
• The ServiceAreasQC replacement layer remains in My content to make it easier for you to replicate your quality control tests. As a result, this layer's content is only relevant in the context of this testing workflow. The only valid reason to share this layer is if you need other people to test the updates before you use the content to update the production layer.

Changes in the replacement that can adversely affect the current layer

The following changes in the replacement layer can result in unexpected behavior in the vector tile layer you replace, especially if you authored other styles for the layer:

• Removing a layer from the map in ArcGIS Pro before publishing the replacement vector tile layer or package.
• Adding a layer to the map in ArcGIS Pro before publishing the replacement vector tile layer or package.
• Renaming one or more of the layers in the map in ArcGIS Pro before publishing the replacement vector tile layer or package.
• Changing symbology on the layers in the map in ArcGIS Pro before publishing the replacement vector tile layer or package.
• If the current vector tile layer is enabled for offline use, ensure that the replacement layer is also enabled for offline use. If the replacement layer does not have the offline mode enabled, the current layer will no longer be enabled for offline use after you replace its contents.

If you make any of the changes listed above in the replacement layer, preview styles to confirm you're okay with the changes before you finish the process of completing the current layer with the replacement layer.

The behavior may vary depending on the changes. For example, when you add a layer, other styles continue to display the layers that were defined before the replacement, but they may not display the added layer unless the style owner re-creates the style.