@Mixture,
Whilst i agree with you that safety is paramount and there should be no ambiguity in clearances issued by ATC, i do not see any if you were cleard
"climb five tousand ft", and the word ft is cut out during the transmition as you would have it, you would still know you are climbing to an altitude since you dont climb to levels in tousands,
And better still if in doubt just ask for the clearance again, why would you want to act on a clearance you arent sure about.
@Checkboard
Point taken on the use of altitude between the word "to" and say "5,000",
but remember at the beginning of the thread poster asked difference between "climb 5,000" and ''climb maintain 5,000'', there was no to in between.
For ATC who are verbose and would like to make clearances like "climb to", then the word altitude would suffice.
I know you have quoted the clearnce for tiger 66, but the ATC would have just said descend two tousand fower hundred feet, in this case no need for use of the word altitude, granted clearance was two four zero zero feet, but even as pilots clearances have to be sensible, thats why you check again if in doubt, when last were you asked by ATC to descend 400ft?