the X value in the InDesign control panel , is the distance between the top left corner of the object and the 0 on the ruler.
the 6 small square in the control panel are the refrence point, which refer to which point on the object this X and Y distance would be measured, so in your screenshot
the reference is top left corner hence the distance is from 0 on the horizontal ruler to the top left corner of the object selected.
ok,i understood that,so how do i space them having 6mm seperation between all the 4 pic icons?
Select all the object box between which you want 6 mm seperation.
Go to Windows-->object and layout-->Align
In the Align panel...., on the bottom under "Distribute spacing" there will be two icons and a section "Use spacing"
In "Use spacing" :- enter "6 mm'
and then clikc on the button for "Distribute horizontally' --(secong one), the first icon is for "distribute vertically" and this will mess up the loyout in your case.
once done check the spacing.
thank you manish,got it,i rarely use that align feature,i forgot it exsisted.