This program is used to give the programmer and ISIS programs a database with which they can reference coverage times for ck and spk kernels. Output will thus be to a pvl file specified in the TO parameter. It should be noted that the user is encouraged to use system preferences when defining pathnames, for example $mgs or $base. If this is not possible, for example kernels are being referenced that are located in a user's development area, absolute pathnames should be used. Relative pathnames using ".", "..", or user-defined environment variables are highly discouraged.

Kernels have different qualities. The lowest quality is nadir, which supplies what may be considered "placeholder" values. Generally, nadir kernels exist to fill in gaps and mimic the instrument pointing at -90 degrees. Since they only mimic pointing data, they cannot be used for SPKs, since these kernels specify positions rather than pointing.

The second lowest quality kernel is predict. Predict kernels are based on the predicted location of spacecraft and thus are subject to error.

Reconstructed kernels are of higher quality than predicts. They are supplemented with information as to the actual position of bodies and spacecraft.

The highest quality kernels are smithed. These generally come from reconstructed kernels that have been corrected even further by an individual institution.

The four levels of kernels listed above are the only ones that will be listed in the database. Kernels are ordered from the lowest quality at the top of the output file to the highest quality at the bottom of the output file within individual kernel qualities, kernels are listed from earliest to latest created file. This is done in anticipation of programs such as spiceinit which read from the bottom of the file for the best kernel.

This program's database is in pvl format, and as such order is significant. The last listed kernel file covering the timespan will be used. Because of this in combination with the individual needs of specific missions, ISIS arrays can be used to control kernel file order.

      For example, using the pure string expression:

      "m01_sc_ext??_rec_nadir.bc ; m01_sc_ext??.bc"

      would result in the listing:

      m01_sc_ext10.bc
      m01_sc_ext10_rec_nadir.bc
      m01_sc_ext11.bc
      m01_sc_ext11_rec_nadir.bc
      m01_sc_ext12.bc
      m01_sc_ext12_rec_nadir.bc
      m01_sc_ext13.bc
      m01_sc_ext13_rec_nadir.bc

          while using the ISIS array expression:

          ("m01_sc_ext??_rec_nadir.bc", "m01_sc_ext??.bc")

          would result in the listing:

      m01_sc_ext10_rec_nadir.bc
      m01_sc_ext11_rec_nadir.bc
      m01_sc_ext12_rec_nadir.bc
      m01_sc_ext13_rec_nadir.bc
      m01_sc_ext10.bc
      m01_sc_ext11.bc
      m01_sc_ext12.bc
      m01_sc_ext13.bc