Well then I must ask, what help file are you looking in exactly???

/help /if returns (among other things):

Combining comparisons
You can combine comparisons by using the && for AND and || for OR characters.

number {
if (($1 > 0) && ($1 < 10)) {
if ($1 < 5) echo Number is less than five
else echo Number is greater than five
}
else echo Number is out of bounds
}

This alias checks if the number you specify, when you type /number <value>, lies within the required range.