All IDs (userid, mediaid, etc) are the same for every Partner. In the past we provided different IDs for each partner, so maybe you still have to convert your IDs if you are such a partner. you will find this link on http://www.hyves.nl/api/manage/

IDs are an 8 byte (64bit) integer, encoded as a hexadecimal string of 16 characters, which means they can be stored internally as 64bit unsigned integers. There is a possibility that we are going to need longer IDs in the (far) future, but such a move will be announced long in advance. Although the IDs can be saved as 64bit integers, we expect the IDs returned to us to be the exact same as we supplied them to you - as a 16-character hexadecimal string; this especially means that "low numbers" should be pre-padded with zeros to be 16 charachters long. If IDs of any other format are received, they will be treated as non-existing IDs.

Something else should be mentioned about IDs: For many objects, for instance media, having the ID enables you to see the object. There is no extra check for security, so it is to the Consumer to make sure that ids retrieved as one user are not automatically shown to another user. See the http://developers-hyves.nl/returnvalues for more information.

Note: sometimes no id is returned (the field is empty). In this case, no foreign relation is present, or you have insufficient rights to see the id. An example is the userid for the default profile image.