In number-based incomplete jinās, one expression contains a letter not present in the other, while enough verbal resemblance remains. The addition may appear initially, medially or finally.
A change in count should be distinguished from a change in letter identity. For instance, «ساق» and «مساق» share a recognisable sequence, with an extra mīm at the beginning of one form. This is not merely a matter of vowels or inverted order.
Morphological descriptions such as prefix, suffix or root letter may explain how a form is built, but the rhetorical classification still compares the complete uttered expressions.