OK, I've read the more thoroughly now. On page 23 you have a list of properties (ie. metadata), some of these should be per-port, and the generic ones (name, authors etc.) should probably follow the qualified dublin core standard. http://dublincore.org/ It makes sense to me that versions should follow the library versioning convention, so that hosts could do substitution where appropriate. The denormal numbers stuff seems a bit low level, I'm not away of any operations you can do on denormal numbers without incurring penalty (maybe delay with no gain, but thats stetching it a bit). Also DC offset, shouldn't the plugin be expected to kill its own DC offset if its desired? There is a standard for describing this kind of structural metadata as well as classifications, but I've gone on about it a lot before (and implemnented support for LADSPA), so I'm not going to mention it here again or the LAD regulars will lynch me :) I wont talk about the VVID voice allocation scheme, because I think David can describe it better. Overall PTAF is supprisingly similar to XAP (which is encouraging), there are just some differences in emphasis. Us LAD people tend to be simplecity freaks. I think its one of the really good things about LADSPA. - Steve