| Symbol | Description | Uses |
| RA_CONST | 3 | |
| RA_FX | 3 | |
| RA_FY | 3 | |
| READ_PAR | 14 | |
| REAL4_IS_SLOW | 23 | |
| REAL_D0_IS_16BYTES | 4 | |
| RECIP_DXC_CONST | 1 | |
| RECIP_DXC_FX | 1 | |
| RECIP_DXC_FY | 1 | |
| RECIP_DXF_CONST | 1 | |
| RECIP_DXF_FX | 1 | |
| RECIP_DXF_FY | 1 | |
| RECIP_DXG_CONST | 1 | |
| RECIP_DXG_FX | 1 | |
| RECIP_DXG_FY | 1 | |
| RECIP_DXV_CONST | 1 | |
| RECIP_DXV_FX | 1 | |
| RECIP_DXV_FY | 1 | |
| RECIP_DYC_CONST | 1 | |
| RECIP_DYC_FX | 1 | |
| RECIP_DYC_FY | 1 | |
| RECIP_DYF_CONST | 1 | |
| RECIP_DYF_FX | 1 | |
| RECIP_DYF_FY | 1 | |
| RECIP_DYG_CONST | 1 | |
| RECIP_DYG_FX | 1 | |
| RECIP_DYG_FY | 1 | |
| RECIP_DYU_CONST | 1 | |
| RECIP_DYU_FX | 1 | |
| RECIP_DYU_FY | 1 | |
| recip_hFacC | Inverse of cell open-depth f[X,Y,Z] ( dimensionless ). | 72 |
| RECIP_HFACC_CONST | 1 | |
| RECIP_HFACC_FX | 1 | |
| RECIP_HFACC_FXY | 1 | |
| RECIP_HFACC_FY | 1 | |
| recip_hFacS | 39 | |
| RECIP_HFACS_CONST | 1 | |
| RECIP_HFACS_FX | 1 | |
| RECIP_HFACS_FXY | 1 | |
| RECIP_HFACS_FY | 1 | |
| recip_hFacW | 40 | |
| RECIP_HFACW_CONST | 1 | |
| RECIP_HFACW_FX | 1 | |
| RECIP_HFACW_FXY | 1 | |
| RECIP_HFACW_FY | 1 | |
| RL_IS_REAL4 | 1 | |
| RS_IS_REAL4 | 1 | |
| RS_IS_REAL8 | 1 | |
| RUNCLOCK_USES_DATE_AND_TIME | 1 | |
| RW_SAFE_MFLDS | 6 |