[a.b.c]			# OK
answer = 42		# OK

[a]			# OK - a was non-explicit and was created by std-table-expr
better = 43		# OK - a is now explicit

[t1]			# OK
t2.t3.v = 0		# OK
[t1.t2]   		# should FAIL  - t2 was non-explicit but was not created by std-table-expr