dunno if there's much to say about it, just look at the code. checvectoss and checkvecthrow are just from the SDK I think.
In CSBotCS look at
CheckGrenadeThrowing(), ( lol, another function where I should add some comments when I have time )
in CBotBase, take a look at the CBotBase :: HandleGOrder() function
( I know Pierre, i'm cheating 
but still grinning anyway 
)