21st release of BioModels Database

Dear colleagues,

We are pleased to announce the twenty-first release of BioModels 
Database (http://www.ebi.ac.uk/biomodels/).

Important changes are happening or announced in this message, so please 
read further.

In this release, 68 new models have been published and numerous existing 
models have been updated. The public version of BioModels Database now 
contains 409 models in the curated and 420 in the non-curated branch. 
Together, these 829 models comprise 130800 species, 151274 relationships 
(which include reactions, rate rules, events and assignment rules), and 
106210 cross-references.

Along with the data release, we would like to announce several important 
changes.

First of all, in addition to the SBML version of each model with 
annotations encoded with MIRIAM URNs, BioModels Database now provides a 
second SBML file with annotations encoded using Identifiers.org URLs. 
Those files can be accessed from the "Download SBML" menu displayed on 
the top left of any model page and from the models archives (now 
provided from the EBI FTP server).

BioModels Database will serve the URN form as the default until the next 
release of the database. Then the URL form will be provided as the 
default. The files with the URN annotations will still be available for 
a while. We encourage software developers to consider the 
Identifiers.org version of MIRIAM URIs for any new development.