Extract the answer to the question from the following context.
Question: A healthcare vehicle is absent from the?
Context: Currently, the Regular Force component of the Army consists of three field-ready brigade groups: 1 Canadian Mechanized Brigade Group, at CFB Edmonton and CFB Shilo; 2 Canadian Mechanized Brigade Group, at CFB Petawawa and CFB Gagetown; and 5 Canadian Mechanized Brigade Group, at CFB Valcartier and Quebec City. Each contains one regiment each of artillery, armour, and combat engineers, three battalions of infantry (all scaled in the British fashion), one battalion for logistics, a squadron for headquarters/signals, and several smaller support organizations. A tactical helicopter squadron and a field ambulance are co-located with each brigade, but do not form part of the brigade's command structure.
command structure
The Regular Force component of the Army consists of three field-ready brigade groups. Each brigade contains several different regiments and battalions, as well as smaller support organizations. A tactical helicopter squadron and a field ambulance are also co-located with each brigade, but these two entities do not form part of the command structure for that particular Brigade Group unit.

Based on this information, it can be inferred that healthcare vehicles (or ambulances) are absent from the command structure for Brigades in Canada’s army. So, the answer is Command Structure.