It's not a file property. Docx is just a zip archive, inside it is docProps/app.xml file. Here's how it looks like:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Properties>
    <TotalTime>4</TotalTime>
    <Pages>8</Pages>
    <Words>1882</Words>
    <Characters>10731</Characters>
    <Application>Microsoft Office Word</Application>
    <Lines>89</Lines>
    <Paragraphs>25</Paragraphs>
    <CharactersWithSpaces>12588</CharactersWithSpaces>
</Properties>

Explorer reads the app.xml file and gets information from it.

You can do the same I suppose, here's an article on that.

In your case you don't want to unpack the whole docx, check this unzip implementation for ObjectScript.

1. Modern editors color variable based on scope. p/t in the beginning is unnecessary.

7. I mean if you develop an API all methods should accept either primitives or ByRefs or json. Not object arguments in one method, primitives in another, etc.

8. If you return %Status always return it. If you return $this always return self.

9. If your class has several instance methods and each has, let's say "debug" argument, remove this argument from methods and add "debug" as a class property.