This is an example from www.keil.com/.../configWizard.html
// <o TIMESTAMP_SRC>Time Stamp Source // <dwt=> DWT Cycle Counter // <systick=> SysTick // <user=> User Timer // Selects source for 32-bit time stamp #define TIMESTAMP_SRC systick
Try inserting a digit into both instances of "TIMESTAMP_SRC", for example "TIMESTAMP2_SRC" and the parser will fail with "Syntax error in Options Block - line xxx: Invalid numeric number." Pregrammers very frequently use #defined values with digits and this is a severe limitation.
Allowing labels to have numbers may be convenient, but it would introduce the potential for users accidentally triggering options.
Numbers in labels are already used 2 major ways. The first skip counting would easily become a headache
skip: <qi>; <oi>; <oi.x>; <si>; <si.x>
This will skip i items. Can be applied to all annotation items marked with a * in this table.
----- Modify a bit: <e.i>* <o.i> <s.i>*
These will modify a particular bit of a value
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I know in your example you hid the number in the middle of a string, but it would be very easy to accidentally put the number at the end of a string, with unintended consequences.
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If you have any suggestions for the Standard, The CMSIS group it an industry wide community. You could leave ideas at github.com/.../CMSIS_5