I've problems checking a field at the point of saving the dataset. Filling the mask it should be possible to TAB through the field (otherwise I could use 'check.input').

I tried:
choice.update.db:
before.choice:
if isspace(tfacp200.orno) then
message("...")
choice.again
endif
In the first step this used to work (the message was shown and no update of the database was done), but I had the problem that after klicking the SAVE button it was not possible to enter the field or save again (even when an input was made to the field before) without showing the message.

How could I solve this problem ?

Solution:
working with the predefined variable 'choice', I inserted in the 'check.input' section:
if choice = update.db then
if isspace(tfacp200.orno) then
set.input.error("...")
endif
endif

(this works because in choice.update.db a 'check.all.input' is called automatically).

You can use the value of before.update.check in a check.input section. The value is 1 if the check is being done as part of the save/update, and 0 otherwise (i.e., during field entry). So, you could structure your check as follows:

check.input:
if before.update.check = 1 and isspace(tfacp200.orno) then
message("...")
set.input.error("")
endif


I hope that helps.