Bookmarks can be created in ArcMap, based on results of the Find Features tool, by selecting a feature from the results list, right-clicking it, and selecting Set Bookmark from the popup menu. In some cases, bookmarks created through this method are unnamed.
There are two causes:
• The new bookmark derives its name from the value of the layer's primary display field for the selected feature. If the layer does not have a primary display field, or if the primary display field contains a null value, the new bookmark will be unnamed.
• If there is a table joined to any layer, and a bookmark is created for one of its features from the Find Features results, the bookmark will always be unnamed. This only occurs with ArcGIS 8.1.