Stored proc and output parameters

Hi, all

Somebody can help me, i want testing output parameters from sp on NULL.
SP.ParamByName('bla bla bla').IsNull work only with input parameters.
And what about output?

Best wishes,
Oleg

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Oleg Kovalevsky
Moscow, Russia
e-mail: ol...@aha.ru
phone: +7 (095) 203-6451
fax: +7 (095) 290-1252