The library contains several thousand subroutines and complete programs which are grouped together by logical affiliation into several hundred program packages. 80% of the programs are written in FORTRAN and the remainder in assembly code, or C usually with a FORTRAN version also available. The language supported is currently Fortran 77.
Each package is assigned a unique code, consisting of a letter and three or four digits. The letter is used to indicate the category in which the program or package resides. A package consists of one or more related subprograms with one package name and one or more user-callable entry names, all described briefly in a Short write-up [1], and if necessary, an additional Long write-up. The terms under which the library material and associated documentation may be distributed are given below.