Checking whether a text box is empty: What is the best way to query whether the user has entered something in a text box?
If the text variable behind the text box ist "t1", you may use

if text[t1]

....

endif

A slight disadvantage here is in cases where the user has entered Space characters only, the "if text[t1]" will be considered "true". You can avoid this by copying the text variable into a normal variable first:

Set V[x] "text[t1]"

if V[x]

 ...

endif