Actually, it's easy to see how bolt lock works even without a cut-away.
Unload the gun, open the hammer, remove the firing pin and bolt stop. Then, hold the grip and push the muzzle against a solid surface so barrel moves back to its rear most position, use the other hand to pull the bolt out.
Look into the square hole from the back of the gun, push the muzzle against the plam and release it, you will see bolt lock "teeth" swings down and up. The two locking cuts under the bolt match the position of the locking teeth on the bolt lock when the bolt is in the closed position.
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If I had said "Canadian Cannon" (Inglis), it would have been my invention. "Luger Cannon" was your invention. Not every pistol was entitled "Cannon" in old Oriental world
Formally accepted nicknames were "Canadian Lu-zi", "Humpback Lu-zi". "Lu-zi" rougly means automatic pistol in Northern Chinese slang. General public did not study ballistics at that time, direct feeling was bigger pistols were more powerful than smaller ones, so entitled "cannon".