create procedure in vs inout vs out parm

I have a simple stored procedure:
CREATE or REPLACE PROCEDURE cafteria.SP_AMUSER(
IN username CHAR(10)
)
EXTERNAL NAME cafteria.SPAMUSERC
LANGUAGE CL
PARAMETER STYLE GENERAL

The question is when the external .NET program calls this if:
1. UserName is defined as INOUT will the .NET program wait for the
completion of the program before continuing?
2. UserName is defined as OUT will the .NET program wait for the completion
of the program before continuing ?
3. UserName is defined as IN will the .NET program wait for the completion
of the program before continuing ? I say no on this one.