In library science, the number of pages in a book forms part of its physical description, coded in subfield $300a in MARC 21 and in subfield $215a in UNIMARC. This description consists of the number of pages (or a list of such numberings separated by commas, if the book contains separately-numbered sections), followed by the abbreviation "p." for "page(s)". The number of pages is written in the same style (Arabic or Roman numerals, uppercase or lowercase, etc.) as the numbering in each section. Unnumbered pages are not described.