Heading levels should go up consecutively, because Interscript numbers all headings automatically. Here's a document with several headings. On-the-fly interscript for test 2 follows.
33: @head(1,'Several Headings') 34: Test with several headings. 35: 36: @head(2,'First Subheading') 37: Under the first subheading is a subsubheading. 38: 39: @head(3,'First Subsubheading') 40: Some details here. 41: 42: @head(3,'Second Subsubheading') 43: Some more details here. 44: 45: @head(2,'Second Subheading') 46: Here's the second subhead. And the last 47: text in the document.