hsc performs a syntax check with your source. It testes it for
things like missing closing tags, illegal nesting or missing
required tags.It also tests attributes for tags, e.g. allowed values
for the ALIGN option of <IMG>.
However, the syntax check of hsc is not very powerful compared to tools that only handle this task.
(Tech. Note: Most errors hsc handles are of the kind "Well, now a
have to program
this if (..) to avoid an enforcer hit/segmentation
fault, why not display an error message now..".)
So if hsc does not report any syntax errors, it doesn't mean that your source is 100% correct. For a more complete and strict test, take a look at the related stuff.