In medieval manuscripts, many superscript as well as subscript signs were used to abbreviate text. Hence, Vietnamese rarely abbreviate their middle names. It is usual for people to abbreviate commonly used expressions. I hope my classicist friends will forgive me if I abbreviate mimeme to meme. Other sources abbreviate "gt" for singular, and "gtt" for plural. It is common within the ATC to abbreviate these ranks by dropping the prefix "cadet". The letter S in "S-train" does not abbreviate any particular word. The names of elevated railways are sometimes further abbreviate it to El or L. Another method employed was to abbreviate frequent words, such as the "nomina sacra". Arthur Brown was absent and Phil May chose to abbreviate the narration between the songs. After the first occurrence, some writers abbreviate by using just "point" or "points". This is also used occasionally to abbreviate the name of the county. It is often a serious obstacle for mountaineers, who sometimes abbreviate "bergschrund" to "schrund". Harry may abbreviate either Harold or Henry. Sinfield also suggested that the band abbreviate their name to PFM, starting with this album.