I see that I've cut off the source I pasted. If you had the full source, you would have seen that the numbers are the default widths in pixels.
This is the initial default value. I.e. those you need before you have a config to load.
The same default as you would define in a constructor or design in the form editor.
Likewise, with the type of the field, there is a default alignment which can be overridden with the attribute.
These are indeed presentation properties and they are defaults explicitly bound to each instance of a field.
The idea is to keep the default properties together with the field declarations instead of having them spread out through the code or defined in the .dfm.
Unfortunately, I cannot use record constants to initialize the titles or specify the secondary sorting columns due to limitations in the language.