"DefaultImage" is a fallback avatar used when no avatar is available (or applicable) for an email address. It may be any public URL (such as a String, URL or CloudObject), or one of the following options:
"mp"
a generic "missing person" avatar
"identicon"
a generated colorful geometric pattern
"monsterid"
a generated "monster" avatar
"wavatar"
a generated "cartoon" avatar
"retro"
a generated "8-bit face" avatar
"robohash"
a generated "robot" avatar
"404"
returns HTTP 404 instead of a default image
"blank"
a transparent PNG image
If "ForceDefault" is True, the Gravatar service will always return the "DefaultImage" fallback avatar.
"Rating" may have one of the following options:
"G"
suitable for display on all websites with any audience type
"PG"
may contain rude gestures, provocatively dressed individuals, lesser swear words or mild violence
"R"
may contain such things as harsh profanity, intense violence, nudity or hard drug use
"X"
may contain hardcore sexual imagery or extremely disturbing violence