ARTCC CTLR DSNDED AN MLG THROUGH LTT ALT WITH LTSS.

Narrative

LTT X WAS PROCEEDING NEBOUND AT 17000 XING THE MILTON 7 ARR RTE INTO LGA. THE HIGH ALT SECTOR HANDED OFF MLG Y DSNDING TO FL190. MLG Y NEEDED TO BE DSNDED TO 13000 (A STANDARD XING RESTRICTION IS MOST OFTEN USED). AT THE TIME MLG Y CALLED ME I WAS DISTRACTED BY A SPACING PROB ELSEWHERE IN MY SECTOR. I SUBSEQUENTLY ISSUED A STANDARD XING RESTRICTION TO MLG Y; THINKING HE WAS HIGHER THAN HE WAS. DUE TO CHOPPY CONDITIONS AT FL190; MLG Y ELECTED TO BEGIN HIS DSCNT RIGHT AWAY AND VERT SEPARATION WAS LOST BEFORE LATERAL SEPARATION WAS ACHIEVED. IN SUMMARY; I MADE A COUPLE OF DIFFERENT ERRORS IN THIS SIT. I MISINTERPRETED THE RADAR DATA BLOCK AND SPD DIFFERENTIAL OF MLG Y DUE TO MY PREOCCUPATION WITH THE OTHER SPACING PROB IN MY SECTOR; I MADE A HASTY DECISION THAT TURNED OUT TO BE AN ERROR IN JUDGEMENT. IN THE FUTURE I WILL NOT DISCONTINUE MY VERT SEPARATION UNTIL LATERAL HAS BEEN COMPLETELY ACHIEVED. I ALSO WILL TRY NOT TO TAKE THINGS FOR GRANTED AS MUCH AS I SEEM TO LATELY. (I.E.; IN MOST CASES; ACRS ON THE MILTON 7 ARR DON'T START DOWN RIGHT AWAY TO MAKE THE XING RESTRICTION).