Six of the main EML's are: CDF, LMML, Targeteam, TML,PALO, and OUNL-EML. 

This ones can be categorize in two groups. The first group consisting of the first four mentioned above which seems more sophisticated specifying learning content and structure. TML can be distinguish as the one that provides for describing highly specific content.   However,  this group appear not to provide for modelling following a pedagogical approach. Also, they are unable of expressing executable knowledge about the model, with the exception of TML. 

The second group consists of PALO and OUNL-EML which can be categorize as the ones closer to the definition of an EML as "a semantic rich information model and binding, describing the content and process within units of learning from a pedagogical perspective". The PALO is limited when defining individual tasks. 

In terms of interoperability, it can be notice that there is low cohesion between EML's included in this two groups because of well marked difference in its elements and attributes. 

About there procedence, all this EML's were developed based on academic initiatives except CDF that was developed by an institute. 

Reference:

1. CEN/ISSS WS/LT Learning Technologies Workshop "Survey of Educational Modelling Languages (EML's)" Version 1; September 19, 2002; Authors: Adrian Rawlings, Peter van Rosmalen, Rob Koper, Miguel Rodriguez-Artacho, Paul Lafrere