hugo/docs/content/en/functions/strings/ToUpper.md

title	linkTitle	description	categories	keywords	menu	function	relatedFunctions	aliases
strings.ToUpper	upper	Converts all characters in a string to uppercase	functions		docs parent functions	aliases returnType signatures upper string strings.ToUpper INPUT	strings.FirstUpper strings.Title strings.ToLower strings.ToUpper	/functions/upper

Note that upper can be applied in your templates in more than one way:

{{ upper "BatMan" }} → "BATMAN"
{{ "BatMan" | upper }} → "BATMAN"