Any way to have access to the detailed (3 or 4 digits) occupational codes in the NHIS data?

I need the detailed (3 or 4 digits) occupational codes in the NHIS data for my research. I have found the following information about the NHIS data: “In order to protect the confidentiality of respondents, NHIS staff removed the detailed 3-digit and 4-digit codes from the public use NHIS files and replaced them with 2-digit recodes for both occupation and industry classifications.” Is there any way for me to have access to the original occupational codes in the NHIS data for my research? Please let me know. Thanks in advance.

The data on IPUMS NHIS are a harmonized version of the original NHIS data provided by the NCHS. Therefore, IPUMS is only able to provide the data as shared by the NHIS staff. Therefore, with regard to the occupational coding scheme, IPUMS NHIS is not able to provide the more detailed 3 or 4 digit codes. It may be possible to access this data on a restricted basis. For this, you’ll need to reach out to NHIS staff directly.