Why need "card" to specify field?

[Andrew Duncan]

In a stack imported from a HyperCard stack, I need to prefix a 
reference to a field with the word "card". E.g. evaluating 'the rect of 
field "x"' in the message box fails with "no such object" but 
evaluating 'the rect of card field "x"' works.

In other Rev stack I've created, the word "card" is not necessary. 
Rereading the Rev Dictionary info for HC programmers, and about 
importing stacks, I see nothing about this. Looking in the dictionary 
for the "field" keyword and the field objects says nothing about this. 
Searching for "card field" turns up nothing.

Why is this extra word necessary?

Andrew
aduncan at expertcity.com