Author: imagic
[Added to the original trac issue at 8.30am, Thursday, 14th November 2013]

I support this enhancement. In Austria many larger buildings have different entries ("Stiegen" - staircase). If those are mapped with addr:unit they either are not found or displayed incorrectly. Some users therefore add the staircase number to addr:housenumber just in order to make nominatim work. On the long run this is counter-productive.

Author: caigner
[Added to the original trac issue at 9.19am, Thursday, 14th November 2013]

I fully support this. In Austria it is essential to have addr:unit working, otherwise the search for addresses like "Haussteinstrae 4/2" is not working. The 2 after the / is the unitnumber.

Author: stefanblag
[Added to the original trac issue at 3.09am, Thursday, 16th January 2014]

This addition is critically needed for the Bulgarian and other maps with soviet-era apartment buildings. For example a building's address may be "1B Batova Street, Apartment Block 5, Entrance (Unit) A". The unit cannot be concatenated to the building name or street number as it might be mistaken for a duplex. In some cases the units might be independent from the street number. For now I keep adding addr:unit tags, hoping for the search to work someday.