What is the proper way to format syntax within ConTeXt?

Question

For some time, I have thought, perhaps mistakenly, that the precise placement or spacing around ConTeXt syntax was unimportant, e.g., under this assumption, all of these should produce the same results:

\setupbodyfont[stsong,12pt]

\setupbodyfont[stsong, 12 pt]

\setupbodyfont    [stsong, 12 pt]

\setupbodyfont[
    stsong, 12 pt
]

\setupbodyfont
    [
        stsong, 12 pt
    ]

I have, however, found some small problems appeared in my document, because I was improperly placing the syntax, e.g., this will not work:

\setuplayout[
    grid=yes,
    margin=10cm
]

This suggests that placement is perhaps important.

I have also discovered some additional spaces appearing in my document, e.g., between ) and ,, and it is likely the result of improper syntax formatting.

• Are there limits to the customization one can apply in placing ConTeXt syntax? Is there a proper way to format the syntax?
• Are the rules for placing %'s at the end of lines exactly the same as that used in LaTeX, as described in Where are the necessary places to be appended with % to remove unwanted spaces?? How does this apply to ConTeXt's use of square brackets?

Answer 1

Spaces are ignored after control sequences (as is normal in TeX), after commas, and after square brackets (either opening or closing).

Spaces in values become part of the value, which may or may not be harmful depending on the type of the value: for dimension assignments this is often ok, but for keyword values it most often results in ignored settings, and sometimes even in errors.

Imho, the nicest way to format ConTeXt's key-value commands is:

\setuplayout
   [grid=yes,
    margin=10cm]