Im afraid that youre correct. Every single requirement MUST be stipulated. Look at it this way. You go down to the car show room in order to buy a new car.
"What do you want"? asks the friendly salesman
"I want a big red one which is fast but also has enough room to get the wife and kids in" You reply.
"There you go matey...a shiny new Vectra" (OMG !!! )
But on delivery you notice there is nowhere to attach the trailer for the boat... Disgruntled you return to the friendly salesman and object.
"But there was no requirment for a towbar....but if you return the car to the garage we can fit one for twice the price you origionally thought it would be.
Same goes for Military (or even Civilian) procurement. If you don't get the requirment right then you are completely buggered. As a good example of this please see this post
http://www.pprune.org/forums/showthread.php?t=233146
That is a very good example of the requirment going wrong
Please ignore the appalling spelling and punctuation..... too much wine