Open XML - Interpreting Group and Shape Positions in Word

A group in a Word document creates the following heirarchy of nodes in document.xml.

<mc:AlternateContent ...>
  <mc:Choice ...>
    <w:drawing ...>
      <wp:anchor ...>
        <wp:positionH ...>
        <wp:positionV ...>
        <a:graphic ...>
          <a:graphicData ...>
            <wpg:wgp ...>
              ...
              <wpg:grpSpPr ...>
                <a:xfrm ...>
                  <a:off .../>
                  <a:ext .../>
                  <a:chOff .../>
                  <a:chExt .../>
              <wps:wsp ...>
                ...
                <wps:spPr ...>
                  <a:xfrm ...>
                    <a:off .../>
                    <a:ext .../>
              ...

To position a shape in a group

Step 1

Use wp:positionH and wp:positionV to position the group.

360000 emu = 1 cm from the edge of the margin is

<wp:positionH relativeFrom="margin">
  <wp:posOffset>360000</wp:posOffset>
</wp:positionH>

relativeFrom="document" makes it from the edge of the document.

Step 2

wpg:grpSpPr/a:xfrm/a:chOff reversed and scaled by a:ext/a.chExt, positions shapes within the group.

360000 emu * (100000 / 200000) = 0.5 cm from the top of the group is

<a:ext ... cy="100000"/>
<a:chExt ... cy="200000"/>
<a:chOff ... y="-360000"/>

Step 3

wps:spPr/a:xfrm/a:off scaled, repositions a shape within the group.

(100000 / 200000) * 360000 emu = 0.5 cm from the left of the group is

<wpg:grpSpPr>
  <a:xfrm>
    <a:ext cx="100000" ... />
    <a:chExt cx="200000" ... />
    <a:chOff x="0" ... />
    ...
<wps:wsp>
  <wps:spPr>
    <a:xfrm>
      <a:chOff x="360000" ... />
      ...

Both wpg:grpSpPr/a:xfrm/a:chOff and wps:spPr/a:xfrm/a:off change shape position.

Opening OpenXML documents

Shift + Right click the .docx file
Open with…
Browse and choose 7-Zip (or any archive tool)

OpenXML Units

1 Point = 20 DXAs
1 inch = 914,400 EMUs
1 cm = 360,000 EMUs