I insist.
Here is an example for .vdx
<Master ID='0'
...
<Shapes><Shape ID='5'
...
<Prop NameU='p' ID='1'><Value Unit='STR'>2</Value>
...
<Shape ID='1'
...
</XForm></Shape>
...
<Shape ID='2'
...
</XForm><Prop NameU='p' ID='1'><Value Unit='STR'>1</Value>
I assigned the value 2 to the master. Now on the page is missing 2, but there is 1.
(I used the old XML format, but it doesn’t matter)
In my file, I see it like this:
visio / masters / master1.xml
<?xml version='1.0' encoding='utf-8' ?>
<MasterContents xmlns='http://schemas.microsoft.com/office/visio/2012/main' xmlns:r='http://schemas.openxmlformats.org/officeDocument/2006/relationships' xml:space='preserve'>
<Shapes>
<Shape ID='5' Type='Shape' LineStyle='3' FillStyle='3' TextStyle='3'>
<Cell N='PinX' V='0.1968503937007877'/>
<Cell N='PinY' V='0.1968503937007853'/>
<Cell N='Width' V='0.3937007874015754'/>
<Cell N='Height' V='0.3937007874015706'/>
<Cell N='LocPinX' V='0.1968503937007877' F='Width*0.5'/>
<Cell N='LocPinY' V='0.1968503937007853' F='Height*0.5'/>
<Cell N='Angle' V='0'/>
<Cell N='FlipX' V='0'/>
<Cell N='FlipY' V='0'/>
<Cell N='ResizeMode' V='0'/>
<Section N='Property'>
<Row N='p'>
<Cell N='Value' V='1' U='STR'/>
<?xml version='1.0' encoding='utf-8' ?>
<MasterContents xmlns='http://schemas.microsoft.com/office/visio/2012/main' xmlns:r='http://schemas.openxmlformats.org/officeDocument/2006/relationships' xml:space='preserve'>
<Shapes>
<Shape ID='5' Type='Group' LineStyle='0' FillStyle='0' TextStyle='0' UniqueID='{F811FFC2-FDBC-4EFF-97CF-13F5FFBC677C}'>
<Cell N='PinX' V='0'/><Cell N='PinY' V='0'/><Cell N='Width' V='1.333333333333333'/>
<Cell N='Height' V='1'/>
<Cell N='LocPinX' V='0' F='Width*0'/>
<Cell N='LocPinY' V='0' F='Height*0'/>
<Cell N='Angle' V='0'/>
<Cell N='FlipX' V='0'/>
<Cell N='FlipY' V='0'/>
<Cell N='ResizeMode' V='0'/>
<Cell N='DisplayMode' V='1'/>
<Cell N='FillForegnd' V='#f0f0f0'/>
<Cell N='LineColor' V='14'/>
<Section N='User'>
<Row N='visDGDefaultPos'>
<Cell N='Value' V='PNT(2,3)' U='PNT' F='PNT(2,3)'/>
<Cell N='Prompt' V='' F='No Formula'/>
</Row>
</Section>
<Section N='Geometry' IX='0'>
<Cell N='NoFill' V='0'/>
<Cell N='NoLine' V='0'/>
<Cell N='NoShow' V='0'/>
<Cell N='NoSnap' V='0'/>
<Cell N='NoQuickDrag' V='0'/>
<Row T='RelMoveTo' IX='1'>
<Cell N='X' V='0'/><Cell N='Y' V='0'/>
</Row>
<Row T='RelLineTo' IX='2'>
<Cell N='X' V='1'/>
<Cell N='Y' V='0'/>
</Row>
<Row T='RelLineTo' IX='3'>
<Cell N='X' V='1'/>
<Cell N='Y' V='1'/>
</Row>
<Row T='RelLineTo' IX='4'>
<Cell N='X' V='0'/>
<Cell N='Y' V='1'/>
</Row>
<Row T='RelLineTo' IX='5'>
<Cell N='X' V='0'/>
<Cell N='Y' V='0'/>
</Row>
</Section>
After this part there's the next shape ID 6 and then 7, 6 is the text callout.