Defensive filter names

A defensive filter receives its name from the -N DefensiveFilterName option when the filter is created. All copies of a global defensive filter have the same name. Global filters and stack-specific filters share the same filter namespace, so a filter name cannot be used for both a global filter and a stack-specific filter. The creation of a stack-specific filter fails if the filter name conflicts with a global filter of the same name, or if there is already a stack-specific filter of the same name in the target stack. The creation of a global filter fails if the filter name conflicts with a global filter of the same name, or if there is already a stack-specific filter of the same name in any stack. This check includes filter names that are in the DMD's persistent memory, even if the corresponding stack is not active.

Tip: If you are manually creating defensive filters, avoid conflicts between global and stack-specific filter names by choosing a distinct naming convention for each, such as starting all global filter names with a G.