Inconsistent info about adding BCP 47 Script tags

[sku21]

In the Keyman docs, the mobile keyboard tutorial recommends adding a Script subtag to your keyboards by default so that Windows will install the keyboard correctly.

However, the BCP 47 page states that it should be omitted, and I also recently received a warning somewhere (sadly no screenshot) stating that the subtag was unnecessary.

I'm curious what the correct answer is, since the pages seem to give conflicting information...

[darcywong00]

It can be quite complicated following BCP 47. The page does say

If your language only uses one writing system, omit the Script subtag.

So it's not a blanket statement for omitting script tag. Just for languages where there's a main script used. Like Latin script for English.

Another example is the Khmer language in Cambodia is written with "Khmr" script, so we only need km for the language.

[sku21]

It can be quite complicated following BCP 47. The page does say

If your language only uses one writing system, omit the Script subtag.

So it's not a blanket statement for omitting script tag. Just for languages where there's a main script used. Like Latin script for English.

Another example is the Khmer language in Cambodia is written with "Khmr" script, so we only need km for the language.

Right... The mobile tutorial I linked says

We recommend that you always put in the script tag unless there is a specific reason not to.

Could this maybe be updated to clarify the reasons why you wouldn't? I don't have much knowledge of writing systems myself, so I didn't know why you wouldn't include the Script tag.