1880 OCC (Occupation Code) value 979 undefined

I’m using full count data from the 1880 census, with the occupation variable OCC. Some individuals are coded with OCC as 979, but this value appears to be undefined in the list of 1880 occupation codes (IPUMS USA | 1880 Occupation Codes). What does value 979 mean here?

I see that for the OCC1950 variable, 979 is defined as “Not yet classified.” Would that be the case for this OCC variable, too? If that’s the case, what does “Not yet classified” mean?

Yes, observations with OCC = 979 in the 1880 full count are those that have not yet had their occupations assigned. This happens if the reported industry or class of worker doesn’t match the occupation; in these cases, we review and potentially reclassify the occupation code. The IPUMS historical team is currently working on a revised version of the 1880 full count file that will include updated OCC codes. Many of the 979 codes are likely to be assigned to one of the non-occupational responses; these are represented in the 1880 full count by OCC codes greater than 300 and include broad categories of non-employed statuses such as “keeping house”, “student”, and “institutional inmate”. You’ll also notice that the majority of these observations have already been assigned similar non-occupational codes for OCC1950. I hope this information proves helpful!