Synatx Error for POS and LEN data in ABAP coding

Hi,

I am writing this small code in ABAP editor. I am facing a syntactical error of Filed Type 'I' does not permit a sub field access.

Please explain this error type and also explain how to clear this error.

Please is my program( Just trying to write system date).

DATA: POS TYPE I VALUE 5,

      LEN TYPE I VALUE 25.

WRITE AT/ POS(LEN) '********'.

SKIP.

WRITE AT: POS 'DATE', 20 SY-DATUM,

           POS 'TIME', 20-SY-UZEIT.

ULINE AT/POS(LEN)

Regards

Shafali Jain