Referencing data in the map

Data references used in map documents, globes, and 3D scenes are stored as map layer properties. Most layers reference data stored in geodatabases or as files on disk—for example, shapefiles, coverages, CAD files, imagery, and so on. Each data reference is a path, and there are a number of alternatives to store that path.

Each time you add data to a map, the path to the data is stored in a layer in the map. When you open your map, ArcMap locates the data it needs using these stored paths. You can view the path of the data represented by a layer in your map by looking at the List by Source view of the Table of Contents or by double-clicking the layer to open the Layer Properties dialog box, then clicking on the Source tab.

If ArcMap can't find the data for a particular layer, the layer will appear in the ArcMap table of contents, but it won't be drawn. Instead, a red exclamation point will appear next to the layer to indicate that the layer needs to be repaired. To learn how to update the path, see Repairing broken data links.

Options for paths

There are several options for referencing datasets using paths. These include:

Full paths

An example of a full path is:

C:\GIS\Project1\Boundary.shp

To share maps saved with full paths to their data sources, your users must have access to the same computer (or replicate your folder structure on their computer).

Note:

Full paths are also known as absolute paths or complete paths.

Relative paths

Relative paths specify the location of the data relative to the current location on disk of the referenced file. An example of a relative path is:

\Project1\Boundary.shp

You can reference data in a folder that's above the folder containing the map. In these cases, the relative path will contain \..\ for each level up in the folder structure to be traversed.

Since relative paths don't contain drive names, they enable a layer and its associated data to be moved to any disk drive without the having to repair the layer's data links in your map documents.

UNC paths

Universal Naming Convention (UNC) paths use a syntax for paths and files on a network of computers. The syntax is:

\\<computer name>\<shared folder>\

followed by any number of directories and terminated with the referenced directory or file name. For example:

\\pondermatic\public\studyarea.gdb

\\billywood\public\streets.lyr

\\omnipotent\shared_stuff\wednesday\tools

Note:

There may be a performance disadvantage when using UNC paths because network file access is typically slower than direct disk access on your local computer (using absolute paths), which can affect map drawing performance for optimized map services. For example, UNC paths can affect performance of web map services.

Specifying the format of paths

You can view (as well as specify) how path references will be persisted in your documents using the Map Document Properties dialog box as follows:

1. Click File > Map Document Properties on the main menu.
2. Check Store relative pathnames to data sources to specify relative paths.
   Tip:

   If you want all your new maps to be stored with relative paths you will need to specify relative paths as the default. Click Customize > ArcMap Options to open the ArcMap Options dialog box, and then click the General tab. Check the option to Make relative paths the default for new map documents. This setting is stored in the registry.

Once you've saved the layer file, you can't change the data source options from absolute to relative or vice versa. The layer will always maintain the data source option that was set for the map document at the time you saved the layer.