There is a limitation on the branch nesting depth that a pipeline may have. The first branch off from a line is level 1. If this branch in turn has a branch, then that branch would be level 2. ISOGEN will currently handle pipelines that contain up to twenty levels of branching. If a pipeline contains more than twenty nested branches, the extraction will fail. This limitation effectively limits the size of the largest system type isometric that can be extracted. This generally does not pose a problem for single pipeline fabrication type isometrics. Note, that the ISOGEN interface identifies a traversal sequence that minimizes the number of nested branches in most cases.