Hello,
They are part of the Alignment Toolbar, used to place/align one object with respect to the other. Of the four options, the first option is used to select the reference object (when selected, the object will have a red box surrounding it) with respect to which any other object can be aligned. The x, y, and z options are used to change x, y, and, z positions of the second object with respect to the selected reference object.
Each of the x/y/z options have 4 sub-options.
Lower Edge: Aligns the lower edge of the second object with the lower edge of the reference object in the x/y/z directions. In other words, the x min/y min/z min of the second object becomes same as that of the reference object.
Middle: Aligns the center of the second object with the center of the reference object in the x, y, and, z directions.
Upper Edge: Aligns the upper edge of the second object with the upper edge of the reference object in the x/y/z directions. The x max/y max/z max of the second object becomes same as that of the reference object.
Stack: It stacks the second object right next to the reference object in the x/y/z directions. The x min/y min/z min of the second object becomes same as the x max/y max/z max of the reference object.
Steps:
1. Click on “Make the selected object the alignment object” i. e. the first of the four options.
2. Select the reference object. Once selected this object will be enclosed in a red box.
3. Select the second object (the object to be moved).
4. Based on how you would want the second object aligned, select the desired options in the x, y, and z directions.
For example, if I have two rectangles. And I choose the blue rectangle as the reference object as shown below:
And then select the red object and choose the x option and then lower edge sub-option. The lower edge of the red object is moved to align with the lower edge of the reference blue object as shown below:
Thank you.