Paragraph IDs can be used to change "current" paragraph
When working with the IWPParInterface, Paragraph IDs make it possible to switch between Next, Previous, Children and Parent Paragraphs.
So you can actually use the property CurrPar to access, evaluate and modify all paragraph in the internal XML like paragraph tree.
a) previous in list (i.e. previous paragraph, cell to the left)
b) first child or 0 (i.e. first cell in table row, first row in table, second paragraph in cell)
c) parent or 0 (i.e parent row of cell, parent table of row)
d) next in list (i.e. next paragraph, cell to the right)
Please do not save the Ptr value to be used at a later time in the application. This can cause severe problems when the paragraph was deleted.
Please also see the low level move methods - they provide a save way to loop all paragraphs in the current document or text block.