How to write messages?

Hi all,

I want to know the various methods of writing messages. I used ...

**1**

IF SY-SUBRC <> 0.

MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO

WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.

**2**

MESSAGE E000(ZCA) WITH LV_MESSAGE.

**3**

data msgtxt(255).

open dataset imp_dat for input in text

mode encoding default message msgtxt.

**4**

data msgtxt(255).

if sy-subrc ne 0.

write: / 'File Open Error'(004),imp_dat, msgtxt.

Are there more? Could you please explain these and others which might exist.

Thanks,

Charles.