The X and Y list boxes contain the following choices:

Absolute from top left (default)

Absolute from bottom right

Proportional

Fixed        

It is also possible to check or clear:

Snap        (cleared by default)

X-horizontal position (only in replacement mode) defines the X-position of the library object when placed on page, during the replacement of an original object. The default value is Absolute from top left. This setting is suitable for all single objects, and all "first" objects in complex structures.

For horizontally stacked objects, e.g. article legs, the X-position of all legs but the first one must be set to Proportional. Avoid other choices.

Y-vertical position  (only in replacement mode): defines the Y-position of the library object when placed on page, during the replacement of an original object. The default value is Absolute from top left. This setting is suitable for all single objects, and all "first" objects in a complex structure.

For vertically stacked objects, the Y-position of all legs but the first one must be set to Proportional. Avoid other choices

hmtoggle_plus1Absolute from top left
hmtoggle_plus1Absolute from bottom right
hmtoggle_plus1Proportional
hmtoggle_plus1Fixed