On page 6 of the 1940 Census Enumerator's instructions (page 4 of the printed manual) paragraph 19 reads:
Nonresident schedule. -- Members of a household who object to being included in the population of their district, claiming that their usual place of residence is elsewhere, are to be enumerated on the Nonresident Schedule. This schedule differs from the Population Schedule in that it includes an inquiry on the location of the usual place of residence as well as the place of residence at the time of the enumeration. It includes the supplementary questions, which are to be asked of all members of households enumerated on the Non-resident schedule.
A Google Search revealed a blog post, 1940 Census: non-resident form on Paula's Genealogical Eclectica with a link to an image. There are also other schedules which can be seen via the instructions for the Family Search indexers.
The 1940 census included several census schedules:
- Population Schedule
- Absent Household Schedule
- Preliminary Population Schedule
- Nonresident Schedule
Those instructions say:
When indexing one of these other schedules, index information for the fields that are available, and then either skip the remaining fields or mark them as blank, according to the instructions in the relevant field helps.
This implies that at least some of the non-population schedules were made available to the Family Search indexers. Are they also available online, along with the images for the Population Schedules? I've read the "about this collection" material on Ancestry.com, the FamilySearch Wiki, and the 1940 Census Website, and it's not clear to me how one might find someone if they were on one of these schedules and their names in the index were not spelled the way you would expect.