General comment: Extensions It seems like there will be a lot of usage of the any elements to extend the interface. For 
instance, I can see [transfer requirements] being used for GridFTP specific settings like streams and buffer size in 
order to tune GridFTP transfers. While the nterface specification appears well defined and it is good to limit its scope
, in practice the extended, implementation‐dependent elements could be significant and undermine the objective of 
interoperability. That’s more of a concern than an objection.