Error while loading pnl json file using mdf_load method about mdf

[mraunak]

Approach to solve the above issue on the MDF part as per discussion:

At each level of the hierarchy in MDF, add 'framework_specific' as an argument in allowed fields of an object that can be included, which will support framework-specific(e.g. PNL, NeuroML) object attributes.
e.g.
Edge in PNL has a 'function' attribute whereas Edge in MDF doesn't have it.
'framework_specific' which would be a dictionary with framework-specific objects. e.g. 'framework':{'pnl_framework':....'} with function attribute in edges

@davidt0x and @Shanka123 please add if I missed something to include

[pgleeson]

I think this is no longer relevant given we have the ability to add generic metadata. closing, but reopen @mraunak if required.