> What input device is used that gives the user the
> flexibility in input format that you described before ?

SMS or GSM data
 
> Maybe you can't change that, but must the user
> have that flexibility ?

Well, people are people. As Josh says -

"A common mistake that people make when trying to design
something completely foolproof is to underestimate the ingenuity
of complete fools.
        -Douglas Adams"

I *could* make the input ASCII conform to a specified format,
but that wouldn't actually change the interpretation or actions
needed, as you have to allow for decimals. It would be unreasonable
to expect a user to enter a battery voltage in xxxxx mV for example

User-input flexibility is desirable (stopping short of "type whatever
you feel like, the PIC will know what you really meant"), interpretation
flexibility is pretty much essential

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