See my Wikipedia user page.

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en-N This user can read and write at a native level in English.
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vb-4 This user is an expert programmer in Visual Basic.
sql-4 This user is an expert programmer in SQL.
c-3 This user is an advanced programmer in C.
lisp-2 This user is an intermediate programmer in Lisp.
html-2 This user is an intermediate coder in HTML.
vbn-4 This user is an expert programmer in Visual Basic .NET.
csharp-2 This user is an intermediate programmer in C#.