Most of the LAS library routines are written in C. However, since LAS application programs are written in both FORTRAN and C, these C service routines must also be FORTRAN-callable. To accomplish this, a bridge routine was written for most service routines. The FORTRAN program calls the bridge routine which in turn calls the C routine. Bridge routines are system dependent due to different implementations of mixed language programming.

The support routines are listed by the names that a C program would use. FORTRAN programs call the bridge routine; For example, a FORTRAN program calls getin() to parse the input image specification, while a C program would call c_getin(). The exceptions to this naming convention are routines which are only C-callable or are the labeled table routines. These exceptions are noted.

Note that FORTRAN passes all parameters by reference; therefore, all of the C service code is written to expect the address of all arguments.

The support routines, when encountering an error, will output a specific error message to the user and return one of the values shown in the description of this routine. Sometimes a support routine will give a bad return status without displaying an error message to the user. Errors that occur with no error message to the user are documented.