HTML content is weighted by the indexing engine in this order:
In addition you can insert markers as HTML comments which define which part of the body-text to include or exclude in the indexing:
The marker is
If there is no marker at all, everything is included.
If the first found marker is an "end" marker, the previous content until that point is included and the preceding code until next "begin" marker is excluded.
If the first found marker is a "begin" marker, the previous content until that point is excluded and preceding content until next "end" marker is included.
If there are multiple marker pairs in HTML, content from in between all pairs is included.