Maybe some confusion?
A single snapshot comprises an HTML file and a PNG (screen shot), both cached.
The snapshot page defaults to an HTML version.
Texts within HTML cached copies are indexed, and can be searched; and cached HTML content is used for the underlying part of an annotated view, but:
* it is not (or should not be) possible to draw new Diigo highlights across cached copies.
is a cached version
PositivePress
priced high for those only interested in page archival