The letters in this field have the following meaning:
[][
S:] the star is a `survey' star
[ C:] an identification chart is provided within the faint
star Atlas (Annex 2, Volume 7 of the printed version)
[ T:] the star is a `survey' star, and an identification chart is
provided within the faint star Atlas
[]The survey is the basic list of bright stars added to and merged with the total list of proposed stars (see `Star Selection', page 5). Its limiting magnitude is a function of the star's spectral type and galactic latitude, and is defined by:
(if no spectral type was available, the break was
taken at 
mag).
Where there was considered to be some possible doubt as to the
identification of the star (e.g. for faint stars, for crowded zones, or
for components of double or multiple systems), charts were constructed
from the Guide Star Catalog (Lasker et al. 1990).