The Tag Copy Maps affect the generation of Order Manager related FIX Messages.
For example, when the application needs to generate an "Excution Report" from an order message (or order replace request message), the execution report may need to copy some fields (such as Symbol, Side etc).
Similar to session handlers, the tag maps are also bound to FIX schema (version). So for a new FIX 5.0+ session (uses FIX XT 1.1 protocol) that supports more than one FIX versions (schemas), each schema has its own set of tag maps.
Also buy side and sell side use different set of tag maps. Those are managed by the order manager settings editor.
The Enterprise Manager automatically generates the default tag copy maps used in QWFIX Order Manager. The maps usually don't need any modification. However, users can always manually modify the map using the GUI tool.
Below is a screen shot of the tag map editor for a FIX 5.0 session that supports 5 different FIX versions (from 4.1 to 5.0SP1).