The absolute maximum rating table in the OP484S SMD datasheet refers to
MIL-STD-1835 for Thermal resistance junction to case :
MIL-STD-1835 can be found at:
In table VI from MIL-STD-1835, Junction to case thermal resistance for the
package designator GDFP2-F14 is 22 degC/W
(Note: The correct package type designator for the specific SMD part number can
be found in the SMD datasheet).