Use of Link rel+type for application discovery

In Link headers / elements, the 'rel' attribute defines the relationship and the 'type' attribute provides a hint regarding the content type of the destination resource. Is it correct to assume that while 'type' does not define a relationship (as in, 'image/*' means 'my pictures'), applications may require that both the 'rel' and 'type' attribute carry a certain value when used.

In other words, is it valid to say "look for a link with rel='a' and type='b' and only if both found, do something"?

I assume yes, but want to make sure this does not violate anyone's view on the use of 'type' in a MUST match criteria.

EHL