Scribal abbreviation by "contraction" and was mostly a Christian usage for sacred words, Nomina Sacra; non-Christian sigla usage usually limited the number of letters the abbreviation comprised and omitted no intermediate letter. One practice was rendering an overused, formulaic phrase only as a siglum: DM for "Dis Manibus" ("Dedicated to the Manes"); IHS from the first three letters of "ΙΗΣΟΥΣ"; and RIP for "requiescat in pace" ("Rest in Peace") because the long-form written usage of the abbreviated phrase, by itself, was rare. According to Trabe, these abbreviations are not really meant to lighten the burden of the scribe but rather to shroud
Index term terms can consist of a word, phrase, or alphanumerical term. They are created by analyzing the document either manually with subject indexing or automatically with automatic indexing or more sophisticated methods of keyword extraction. Index terms can either come from a controlled vocabulary or be freely assigned. Keywords are stored in a search index. Common words like articles (a, an, the) and conjunctions (and, or, but) are not treated as keywords because it's inefficient. Almost every English-language site on the Internet has the article ""the"", and so it makes no sense to search for it. The most popular search engine,