in the industry classifications tables provided on the website, 00000000 codes are indicated to be N/A - less than 16 years old, unemployed, etc. But in the 2002 to 2004 ACS samples (IPUMS-USA), some of these observations have IND codes corresponding to various industries. does it mean that IND codes have a larger coverage?
more generally, I’d be interested in finding correspondence tables between the IND classification used in the ACS samples and commonly used classifications, such as ISIC or SITC codes. Any help in this would be much appreciated.