Blocker Currently the prose specification defines no limit for namespace names, and the CSDL schema definition limits them to 512 characters.
Both the prose spec and the schema limit simple identifiers to 479 characters.
Apparently the C# compiler accepts only 511 characters for both variable names and namespace names, so 512 is too long for namespaces, and 479 is oddly short for a simple identifier.
JavaScript on the other hand has no limit for variable names.
Most people I talk to are concerned about payload size, so keeping propery names short is a benefit.
How about 50 for SimpleIdentifier and 500 for Namespace? Or even go down to 30 and 300?
30 and 300 seem a bit arbitrary.
SQL specifies 128 for a simple identifier; perhaps we should follow that.
Let's haggle 
Perhaps suggest a maximum length for interoperability?