Agents operate in units that are specialised to accomplish specific tasks.
In general, the Master of the Shard assigns a mission to the appropriate Division Head to choose a unit, units, or unit partial to fill.
Overview of the 'Unit'
Agents of the Shardic Order operate within several layers of subdivisions, first by geography (local versus external), second by Division, and third by Unit. These units are generally unnamed and unnumbered, and for the most part the least visible to the public eye, yet they are the factions in which Agents spend the most time.
Units comprise of Agents from varying Departments, assembled by training officers and their Division Heads to be specialised to handle or accomplish specific tasks. In general, Agents within a single unit would have gone through training together, or within three or four years of one another. As a result, most units become very close-knit cohorts that Agents will identify as their family throughout their careers in the Order, and often thereafter as well.
The number of units per Division, and the size of each unit varies across all Divisions according to the needs of the unit. With the exception of Division Gryson, which generally operates as a single unit of several hundred Agents, units generally cap at about 25 Agents. Units are singularly identified by their leaders.
The Division Kadan is the only other Division that does not have units.
When the Master of the Shard decides that Agents need to be mobilised to handle a situation, he/she will write an order for the mission and assign it to the appropriate unit, units, or unit partials.
Unit partials are, as the term implies, small subsections of the unit.
Unit partials are assigned missions when a mission does not require an entire unit.
Though the Master has the authority to send specific Agents on a mission, Masters very rarely know every unit and Agent well enough to make such a judgement call. In fact, the Timewalker was the only Master who was fond of exercising that authority. (She was also fond of handpicking unit partials.)
Instead, most Masters will often simply pass the order to a specific Division with recommendations, since Division Heads have a more intimate understanding of his/her Agents and the capabilities of their units. The Division Head will then choose the unit, units, or unit partial to fill the mission order.
Only then are Agents sent out on the mission. The mission is directly overseen by the assigned unit leader (or a tesared- officer in the case of multiple units).