Besides the numeric, character, and logical parameters we have seen so far, there is another class of parameter to which some of the PAR routines may be applied. In ADAM, these are parameters that specify the name of an HDS or Fortran data file, a magnetic-tape or graphics device.
The values are obtained from such parameters by calling special routines within the particular subroutine library that connect to the ADAM parameter system. The routines are usually called fac_ASSOC, where fac is the facility name of the package, e.g. NDF_ASSOC accesses an NDF whose name is found via a parameter, and SGS_ASSOC obtains the name of an SGS graphics device. There are also fac_CANCL routines that free other resources opened by the corresponding fac_ASSOC routine, and therefore you should not use PAR_CANCL to cancel parameters obtained by using an fac_ASSOC routine. However, it is possible and quite legitimate to call PAR_PROMT to set a prompt string for this class of parameter, or to call PAR_DEF0C to set the dynamic default, or to find the state of a parameter using PAR_STATE.