The fuel load for left (wing), center and right (wing) fuel tanks in kilograms. The engines only ever draw fuel from the wing tanks (left and right). The center tank only pumps fuel into the wings. Under normal running, the wing tank levels will not drop until the center tank is empty.
My interpretation is the Center Tank automatically feeds the Wing Tanks and the Wing Tanks feed the engines. The Wing Tank fuel quantities therefore don't/shouldn't reduce until "after" the Center Tank has first been exhausted. There should be no risk of fuel starvation or consequential engine flame out/s when the Center Tank is exhausted .... although the panel may auto-generate an alert to the effect that the Center Tank is low or empty ... MEANING .... when the Center Tank is exhausted the engines will/should then "automatically" continue feeding from the Wing Tanks and without need of any personal intervention or panel reconfiguration.
I don't want to seem like I'm fobbing you off, but, can I refer you (please) to the forum based BAC ONE-ELEVEN manual as follows ....
It's just with 2 people "here" down recently with COVID, one of my own daughters still in recovery from COVID too, along with personal ongoing health issues as well, plus (as if the former weren't already enough) I've colleagues caught up the the current Ukraine crisis too (К черту ПУТИНА) .... now's just not a good time for me/FS support-wise. Therefore I'll be attending to product support "as is convenient" for me to do so. This's also ("partly") why the HJG website update is currently late/overdue.
Sorry .... but "normality" will (hopefully) resume here ASAP