Variable names must be uppercase?

[Sjoerd82]

This does not work:

type Configuration struct {
	port              int      `env:"POSTGRESSE_PORT"`
	dburi             string   `env:"POSTGRESSE_DBURI"`
	channels          []string `env:"POSTGRESSE_CHANNELS"`
}

But this does:

type Configuration struct {
	Port              int      `env:"POSTGRESSE_PORT"`
	Dburi             string   `env:"POSTGRESSE_DBURI"`
	Channels          []string `env:"POSTGRESSE_CHANNELS"`
}

Is there a good reason for this?
Yes->Document it
No->Bug