A new Chandra format for encoding functional forms in FITS files. Currently these are used to compactly describe the ACIS RMF. Standard RMF files are then generated from these using the mkrmf tool.

Note that the CIAO tool mkacisrmf is used to generate RMFs for all Chandra observations taken at the -120 C focal plane temperature. Only older datasets require the use of the tool mkrmf.