Subfile is a group of records in a record format and can be read from or written to the display in a single operation.
This sentence will make sense if you are an
AS400, iSeries IBM i Software developer.
If you are not then it probably sounds like gobbledy gook.
So what it means is - when a program builds a list of information and then wants to display it on the screen its called a subfile. Think of it as a collected set of information that is going to be displayed to the user. The user can generally scroll up and down through this list of information.
Example - a program wants to display a list of all the books you have purchased from Amazon. The information could be collected and formatted into a subfile and then the subfile would be displayed to the user
CHECK(ER) ER - End of Record.
Which means that if you define a 10 character field on the screen, then when the data entry clerk (or clerkette) enters the data into that field the moment they key the tenth character (or press FIELD EXIT) then the program will continue just as if ENTER has been pressed.
... and what will be the effect if you define this keyword at file with out any parameter values ?
This file, record or field level keyword is used to change one or more input defaults for input capable fields. If you define this keyword at file level without any parameter then the underline will be suppressed.