Historical version. PostgreSQL 10 has reached end of support. 2022-11-10. See the current manual.
43.3. Data Values in PL/Tcl
The argument values supplied to a PL/Tcl function's code are simply
the input arguments converted to text form (just as if they had been
displayed by a SELECT statement). Conversely, the
return and return_next commands will accept
any string that is acceptable input format for the function's declared
result type, or for the specified column of a composite result type.
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