# Parallel matching groups

With complex regular expressions, you might need to set up different regular expressions for matching in parallel groups.

You can set different regular expressions to be matched in parallel groups within one Situation Context. Normally, manual Situation group definitions are not needed and the engine automatically compiles all your custom Situations in the same group (group 0). Manual group definitions are needed if the policy upload fails due to fingerprint/DFA compilation problems that can occur with complex regular expressions.

To use grouping, add a new preprocessing tag to the beginning of the regular expression.

Table 1. Preprocessing tag for setting a group for matching
Syntax | Description
--- | ---
`#!!GROUP(X)` `Comment` `#!!#` | 'X' is the group number from 0 to 7. The comment is optional. If you do not specify the group with this tag, the Situation is processed in group zero.