The first door of Anuyoga (exposition);
an introduction to a treatise or a scripture through which the initial information about its title, subject-matter, sections, chapters etc., can be gathered.
upakramaṇamupakrama iti bhāvasādhanaḥ, śāstrasya nyāsadeśasamīpīkaranalakṣaṇaḥ, tip akr amy ate vā'nena guruvāgyogenetyupakrama iti karanasādhanah.
(Anu 75 HāVṛ p.27)