A Syriac codex is built from quires, gatherings of folded leaves sewn together, and a scribe numbers them. The numbers are written in letters, because Syriac letters carry numeral values, and the hundreds that qaph opens are what a long book needs.
This is not a marginal detail of manuscript production. It is the mechanism by which a book survives being taken apart. Bindings fail, leaves come loose, quires are lost, and a numbered gathering can be put back in its place centuries later by someone who does not read the language. A quire signature also tells a cataloguer that a book is incomplete, and which part is missing, which is a different and more useful statement than noticing that a text breaks off.
Because the numbering is written in ordinary letters, a string on a page may be a word or a figure. Marks distinguish them where a scribe bothered to write them. Where none were written, context settles it almost always, and where it does not, an editor decides and a careful edition says which.
The Syriac manuscript tradition matters out of proportion to the size of the communities that kept it, because a good deal of early Christian literature survives in Syriac and in nothing else, and because Syriac translators carried Greek philosophy and medicine into Arabic. The apparatus that let those books be copied accurately, including the letters doing duty as numbers, is part of why they are still here.