Here are the rules: https://golang.org/ref/spec#Exported_identifiers https://golang.org/ref/spec#Exported_identifiers An identifier may be exported to perm

Here are the rules: https://golang.org/ref/spec#Exported_identifiers https://golang.org/ref/spec#Exported_identifiers An identifier may be exported to permit access to it from another package. An identifier is exported if both: the first character of the identifier's name is a Unicode upper case letter (Unicode class "Lu"); and the identifier is declared in the package block or it is a field name or method name. All other identifiers are not exported.