Difference between species ROOH and MEPX in cb6_ae7

CMAQ Chemistry and Aerosols
1

There are two species which differ in symbol and molecular weight but have the same long name in cb6_ae7 species table at https://github.com/USEPA/CMAQ/blob/master/CCTM/src/MECHS/mechanism_information/cb6r3_ae7_aq/cb6r3_ae7_aq_species_table.md:

The GC namelist for cb6r3_ae7_aq has the following gas phase species.

Model Species     Definition           Molecular Weight     Explicit or Lumped
MEPX 	         methylhydroperoxide 	48 	                        E
ROOH 	         methylhydroperoxide 	90.1 	                    E

When I search ‘methyl hydroperoxide’ in pubchem, I see a compound called CH3OOH (or CH4O2) with molecular weight of 48.041g/mol, which seems to suggest MEPX is methylhydroperoxide. If so, what compound is species ROOH representing in CMAQ?