Syntax question

[etlghh@garbo.ericsson.se (Geoffrey Hollingworth)]

Hi

I am currently researching into real time languages and hope
you ada experts can explain something to me.  I apologise for
my lack of knowledge in ada.
When binding formal parameters with actual parameters the '=>'
operator is used, irrespective of whether the formal parameter
is declared as IN, INOUT or OUT.  Is there a reason for this ?
If I proposed an alternative syntax where "=>" indicated the FP
was an IN parameter, "<=" to indicate an OUT parameter and "<=>"
to indicate an INOUT.
Then the caller of the procedure/function would have explicitly
had to understand to direction of the parameters and at the same
time increased the readability of his/her code.
Is there a fundamental flaw in this line of thinking ?
Does ada manage this problem via a different mechanism ?

Any information, historical or otherwise, would be a great help
to me and greatly appreciated.

thanks

/geoff