:term:`MRCC_LEVEL <MRCC_LEVEL (MRCC)>` """""""""""""""""""""""""""""""""""""" Maximum excitation level. This is used ONLY if it is explicity set by the user. Single-reference case: all excitations up to this level are included, e.g., 2 for CCSD, 3 for CCSDT, 4 for CCSDTQ, etc. This becomes ``ex.lev`` (option \#1) in fort.56. * **Type**: integer * **Default**: 2