You can position a datum point by selecting two points on the model; ABAQUS/CAE creates the datum point midway between the two selected points.
To create a datum point midway between two points:
From the main menu bar, select Tools
Datum.
The Create Datum dialog box appears. The dialog box outlines the types of datum geometry you can create.
ABAQUS/CAE displays prompts in the prompt area to guide you through the procedure.
Tip:
You can also create a datum point using the 
tool, located in the module toolbox. For a diagram of the datum tools in the toolbox, see “Using the Datum toolset,” Section 40.2.
From the list of types at the top of the dialog box, choose Point.
The Method list indicates the methods you can use to create a datum point.
From the Method list, select Midway between 2 points and click OK.
From the part or assembly in the current viewport, select two points.
The datum point appears. You cannot modify a datum point created with this method; you must delete the old point and create a new one.
