This function marks cell cellid as being non-sparse. Some table models, such as CALS, allow sparse markup, where some cells of a table are not explicitly described in markup. We add “generated” cell markup to the document when we read a sparse table so that there is markup underlying every table cell. When we save a document containing a table, we delete this “generated” markup, unless the cell has acquired content, attributes, or some other reason for existence. This function allows the user to require that the markup corresponding to a cell NOT be discarded, even if it is generated markup.

Note that we never strip out “real” markup, only generated markup.