I am looking at the Empstat variable for Egypt in the years 1996 and 2006.
“Not in Universe” implies that the person was not a part of the population to which the question was directed. The target population is called the question universe, and you can tell who was meant to be included in the universe in a variable’s Universe Statement. As you can see from the link, for Egypt, persons under the age of 6 would be considered “Not in universe.”
A general discussion of “Unemployed” as well as more specific language for each country is available near the bottom of the Comparability Statement. The section regarding Egypt also makes some mention of the “Inactive” designation. You can gain further information on how the question was posed and prompted by looking at the Questionnaire Text. Comparing the questionnaires to the Detailed Codes, you can see that for Egypt, those who indicated that they were seeking work in 1996 were coded as “Unemployed” while respondents who indicated that they were housewives, retirees, students, elderly, disabled, do not desire to work, or “other” in 2006 were coded as “Inactive.”
Finally, “Unknown” is generally applied to a respondent when they did not complete the form or their response was unclear (e.g. filled in multiple responses, etc.).
I hope this helps.