The description of SPLOC refers only to spouses, who are located in the hoseuhold using the rules described under SPRULE. However, SPRULE refers to “spouse/partner” as does the detailed description of recent changes to variables. Does SPLOC in the ACS 2011-15 file include the location of unmarried partners in a household?
The SPLOC variable does allow spouse links between unmarried partners, but only if the unmarried partner is directly identified as such in the RELATE variable, meaning that we can only identify unmarried partner couples if they include the householder and the source data included “unmarried partner” as a valid RELATE code (1990 onward). All of these spouse links will be identified as SPRULE==21 “Householder to Partner”.
This is described in the detailed “New Family Interrelationship Variables” document, as you noted. I agree that it may also be helpful to include this detail in the SPLOC comparability section. I will pass this along to the IPUMS USA team so that they can include this update in their next release.