Feature wish: Semi-colon value separator support

[Nudin]

According to API 0.6 nodes with several functions – for example pub and cafe – should be tagged as key=tag1;tag2 in this example it's amenity=pub;cafe.¹

If I search the XAPI for amenity=pub I won't find the points tagged as mentioned. To get them I've to search for amenity=pub;cafe – but because I can't search for all combination it is impossible to get all objects taged as for example pub.

I propose having the following syntax added for this:
…/api/0.6/[key~tag1] => bringing all objects with tag1 mentioned in the key
whereas
…/api/0.6/[key=tag] => still behaves as in the past.

Alternatively you could also allow wildcards in an search: …/api/0.6/_[key=_tag1*]

[iandees]

I am very unlikely to implement this for several reasons:

1. It's very hard to make such a query fast.
2. The key/value tag idea is essential to OSM, the semi colon-separated list of values is not.

[Nudin]

I understand reason 1 but don't understand reason 2. There is currently NO useful possibility to tag things with more tahn one value, so there's no possibility to tag most of the POIs right.