About edit sessions
Editing occurs in an edit session. During an edit session, you can create or modify vector features or tabular attribute information. When you want to edit, you need to start an edit session, which you end when you're done. Editing applies to a single workspace in a single ArcMap data frame, where a workspace is a geodatabase or a folder of shapefiles. If you have more than one data frame in your map, you can only edit the layers in one data frame—even if all data is in the same workspace. Although you can edit data in different coordinate systems, it is generally best if all the data you plan to edit together has the same coordinate system as the data frame.
There are two ways to start an edit session: by clicking the Editor menu on the Editor toolbar or by right-clicking a layer in the table of contents. If you use the Editor menu to start editing on a data frame that contains data from multiple workspaces, you are prompted to choose the workspace to edit. If you right-click a layer in the table of contents, you automatically start an edit session on the entire workspace containing that layer.
Edits are temporary until you choose to save and apply them permanently to your data. You can also quit an edit session without saving your changes. Just saving a map document does not save the edits to the features—you need to specifically save the edits in your edit session. When you save edits, you write them to the data source, or a database.
Errors you might receive when you start editing
When ArcMap encounters problems starting an edit session on the data you chose, a dialog box appears providing additional information. You can receive errors, warnings, or information messages.
- Errors prohibit you from starting an edit session. You are unable to edit any data until you resolve the issue. You can receive an error message if you have no data sources that are editable, there is a licensing issue (such as attempting to edit certain types of geodatabase features while using ArcView), or you have certain layers inside a basemap layer.
- Warnings allow you to start an edit session but prohibit you from editing certain items in the map. You need to resolve the issue with that particular layer or table before you can edit it.
- Information messages provide additional suggestions to improve performance when editing. You are not required to correct the issue to edit that layer or table, but it is recommended that you do so. For example, if the data you chose to edit is in a different coordinate system than the data frame, an information message appears informing you of this. You can edit data that is in a different coordinate system than the data frame in which it is displayed. However, some editing tasks may give you unexpected alignment or accuracy problems.
If you are using an ArcView license of ArcGIS, you can edit any data that was created using ArcView in a file or personal geodatabase. However, you cannot edit data from connections to ArcSDE geodatabases, feature classes that participate in geometric networks or geodatabase topologies, feature-linked annotation, relationship classes, dimension feature classes, or parcel fabric layers. If you need to create or edit these types of data, you should upgrade your ArcGIS license to ArcEditor or ArcInfo.
A shapefile supports one person editing it, but many people can read it at the same time. Attempting multiuser editing of a shapefile may cause data corruption.