process-start condition?
     action*

A rule to be performed before all other processing.

A process-start has several special stream-related properties. Streams opened in process-start rules without specifying the domain-free open modifier can be written to by:

• cross-translations and down-translations (all rules).
• up-translations, context-translations, and process programs (all output processor rules).

Similarly, process-start rules can write to streams opened with the domain-free open modifier, or to any stream opened in:

• cross-translations and down-translations (all rules).
• in up-translations, context-translations, and process-programs (all output processor rules).

Changing groups in a process-start rule has the following effects:

• in a cross-translation or a down-translation, this can affect any following rule.
• in an up-translation, context-translation, or process program, this can only affect output processor rules.

Of course, changing groups never affects a subsequent rule if it is done within an action preceded by a using group as prefix.

Changing groups can affect a process-start rule as follows:

• in a cross-translation or down-translation, if it is done in any rule.
• in an up-translation, context-translation, or process program, but only if it is done in an output processor rule.