framesPerSecond in Nuke

This question is more Nuke specific, but since there are many users of 
nuke here, I thought I might ask.  I was wondering if Nuke saves out the 
framesPerSecond atttribute when saving OpenEXRs.  Currently, my viewer 
reads the attribute to set the FPS of playback.

I have a user of Nuke that has the issue that the framesPerSecond 
attribute does not get saved in his images.  He tried creating a dummy 
attribute but it only creates a string attribute, not a rational one.

I wonder if this is a known limitation of Nuke (strange) and how are 
people working around it or if there's some secret recipe to have it 
spit out a framesPerSecond attribute.

Thanks.