When I called flickr.photos.setDates as documented at http://www.flickr.com/services/api/flickr.photos.setDates.html, with a date_posted value of 1185684650 (which the UNIX timestamp of a date in July 2007) I received an undocumented response, code 4, error message "Invalid date_posted". What does this error mean?
Flickr has an undocumented restriction on date_posted (and raises an undocumented response to this restriction). The restriction is that date_posted must be a time after the user in question joined Flickr (which for me was later than July 2007).
Source: http://www.flickr.com/groups/api/discuss/72157633978736704/
This is frustrating because I want to upload some old photos to my photostream via the API and want them to appear in at least approximately the right order in my stream. I am going to need to do something along the lines of spacing the date_posted values out throughout the first day after I joined Flickr.