[1] [CITE@en[''''''[''''''WebIDL'''''']'''''' Remove string constants]]
( ([[Anne van Kesteren]] 著, [TIME[2011-10-20 11:25:57 +09:00]] 版))
<http://lists.w3.org/Archives/Public/public-script-coord/2011OctDec/0040.html>

[2] [CITE@en[Disallow constants to be null (#686)]]
([[saschanaz]]著, [TIME[2019-03-15 21:08:24 +09:00]])
<https://github.com/heycam/webidl/commit/c57bdf88df351cbc0f2b76cf64fdb2a166d9d485>

[3] [CITE@en[Disallow constants to be null by saschanaz · Pull Request #686 · heycam/webidl]]
([TIME[2020-01-12 11:45:30 +09:00]])
<https://github.com/heycam/webidl/pull/686>

[4] [CITE@en[Investigate removing nullables from allowed constant types · Issue #448 · heycam/webidl]]
([TIME[2020-01-12 11:46:36 +09:00]])
<https://github.com/heycam/webidl/issues/448>