written abbreviation used to show when someone has signed a document for a person who is not available to sign it

I hope to hear from you soon. Yours sincerely, Chris Smith, pp Rebecca Collings. 望你尽快回信。你真诚的克里斯•史密斯，丽贝卡•科林斯代签。

written abbreviation for pages

This matter is discussed in more detail on pp. 101–123. 这个问题在101到123页中有更详细的论述。