The COUNT_FIXED keyword is used with the ASGRID keyword to specify that the user cannot delete or insert rows to a grid. The number of rows is fixed.
Example
In the following example, an association between classes has a row in the grid for each class that the association attaches to (normally two, but can be three or more if additional classes are attached to the association line; this behavior is hard-coded). Because of the COUNT_FIXED keyword, users cannot add to or delete rows in the grid.
Contrast this with other grids, for example the Use Case Step grid, wherein users can add new steps or delete steps from the grid.