The lines separate categories of submissions. To create a section in the submit menu (separated by lines) you use a new category specifier.
"category" is defined either in SimpleCmd constructor or as an attribute.
cmdjob = SimpleCmd('My submission simpleCmd',
category='Some_category',
hasRange=True,
rangeRequired=True,
canChunk=True,
help='Help for this simpleCmd',
postDialog=postDialog)
or
cmdjob.category="Some_category"
The Category list is sorted.