Based on the brief spec and it being identical in appearance to others I've met, it's a simple coil energised to hold the plate against the electromagnet.
It releases when current is broken. As noted in the data sheet, holding force is 1200 pounds at rated current. This will be approximately proportional to current so you can get eg ~600 pounds hold at half voltage.
Note that there are 12V and 24V versions of the AEM10010.
Do not apply 24V to the 12V version :-)
While some electromagnets may state currents for either 12V or 24V on the same coil it is clear that this is not what they mean here as the 24V current at 250 mA is half the 12V current of 500 mA. ie constant 6 Watts. Turns on the 12V version will be double so that the Amp-turns is the same in both cases.
Brute force intrusion detection: For extra points weaken the current to the point where you can force the door against the magnet by using ultra-violence. THEN when the door opens without the magnet being turned off declare an intrusion :-). (Intrusion detection in this way is standard).
Anti brute force latch:
If you want to foil the brute force intruder you can have a simple secondary "door stop" which when deactivated stops the door if it opens say 20mm but it can be attracted away from the door by an electromagnet. This effectively serves the role of a traditional "door chain".
In a case of a power failure or brute force impact the door can be opened BUT stops after say 20mm on the secondary latch. Because this usually never touches the door in normal use it can be simple and need not have tight tolerances.
This does mean you cannot get through the door in an emergency with power off, as is the case with the magnetic plate latch alone. This may be useful or dangerous depending on your circumstances.
I'm using a reed switch to check when the door is open / closed
Wiring cut/short tamper detection:
For still more points, as it were, include a series resistor R1 in the reed switch housing and a parallel resistor R2 across the reed switch, with their presence not being visibly obvious. Then, when the reed switch is not operated you see R1 + R2 and when it is obvious you see R1. BUT if you cut the wire you see O/C and if you short the wires you see S/C so you know in both cases that there is tampering occurring.
More points: Make the reed switch wiring run visible at some point so people may try and tamper.
And more: Make wiring that appears to be reed switch wiring visible with a tamper detector so tampering is detected but it cannot affect the actual circuit.