Topic: version 4 MAXScript Language Improvements / User Interface/ Command Panels and Rollout Pages
You can control the grouping of rollups for a plug-in by supplying a category:<integer> header parameter, before the opening parenthesis of the rollout body.
Example:
rollout foo "Frabulator" category:3
(
....
)
Category number orders the rollouts.
See also
Rollout User-Interface Controls
Rollout User-Interface Controls Types
Rollout User-Interface Controls Common Properties
Customize The Order of Rollup Pages