Horizontal models have two detachable dovetails: long on the underside, and short on the upper, slanted side. Vertical models only have the long dove tail.
They can be removed by the customer if they get in the way. And, they can be replaced if necessary. You will also have to remove the longer dovetail should you ever have to adjust the travel limit screw which is hidden beneath it.
The long dove tail has been sheared off in this example.
The dove tails are hardened steel and will almost certainly never be damaged. But, they can break off and the results are disastrous. The screws that hold the dove tail onto the body will probably be stuck in the body or the threads will surely have been rendered useless. Trying to remove them is futile. Replacing the body is an expensive option.
Note: You may be able to work without the dove tail since the indicator still has a mounting stem.