[RTTY] What is that funky sound?

[G. E. Janssens - K5WW]

Hi all.
 
Reading all the emails about macros reminded me of something I wanted to ask a few months ago: for some time now I've been hearing a strange sound being transmitted, from many stations, right before the RTTY transmission starts. I recorded it a few months ago, but have misplaced it by now, sorry.
 
It appears to be different for every caller, varies is lenght and tone. Which makes me think it's some kind of "digital" ID. 
 
It's quite annoying, really. It often covers up other callers, and - needless to say - is totally useless in a contest. Looks like it can last for as long as two seconds!
 
If you've heard it too, and some surely must have, I'd appreciate an explanation, link to where it comes from, what program generates it, etc. This garbage gets on my last nerve, much more so than "bad macros".
 
Speaking of macros, though, if I may add my two (3?) cents: more and more I see folks dropping the "DE" when they call me. That is all fine with me; but they drop everything (!) and I find that when the first character they transmit is the first letter/number of their call I have to wait for the second transmission of their call before I can copy it. If they send it twice, at all. I'm all for keeping transmissions short; but making them too short only gets you and "agn agn??" in return. I'm starting to think that very short macros are nothing but a waste of time.
 
And I saw someone mention the "...." at the start of a transmission. That just shows in which stable they were bred: the PSK stable. Watching the "fantastic four" (aka. HK0NA) this evening; they seem to have been eating the same oats. Oh well!
 
Really, that "ID" thing, I'd like to know where that comes from!
 
73,
 
Erik - K5WW