The jargon in this case involves two issues:
The first is Datalink - this is the language used that is sent to the Beogram by the Beomaster or Beocenter. It can be seen to be fitted to all Beograms with a 7 pin DIN plug except a few early versions which come from the very early 80s - Beogram 4004 and 2400/2/4 essentially. All decks after these can be used except those fitted with an RIAA - next bit of jargon!
An RIAA is an amplifier that boosts the signal from a record player up to the same level as a CD player and also makes the frequency response flat. The normal output from a record player will be very low and there will be very little bass. This is all related to the way records are cut and the RIAA is usually fitted to the amplifier on which there will be a dedicted input for record players. With the introduction of CD, many companies decided records were a thing of the past and dropped the dedicated input. This gradually happened to B&O as well but there was another technical reason for putting the RIAA in the record player instead of the amplifier - there was more room and the cable from the record player to the amplifier could be longer. Therefore some Beograms have a built in RIAA and again will not work with your Beocenter 9000. Interestingly, the pin used for Datalink also changes so they won't work with the Beocenter 9000 anyway! The decks so fitted are the Beograms 4500, 6500 and 7000. The one you have chosen is fine!