According to these conventions, tag strings are a concatenation of optionally space-separated key:"value" pairs. Each key is a non-empty string consisting of non-control characters other than space (U+0020 ' '), quote (U+0022 '"'), and colon (U+003A ':'). Each value is quoted using U+0022 '"' characters and Go string literal syntax.

Also, the inspection checks that fields with tags are exported.

Example of a valid tag:

type Example struct {
  Field int `json:"field" xml:"demo"`
}