Default thumbnail resolution. Provides a default for the thumbnail object resolution in case a particular catalog record does not contain a valid catalog::ThumbRes value.
Used only for thumbnail requests ( req=tmb ) and when catalog::ThumbType=3 .
Real number, larger than 0.Typically expressed as pixels per inch, but may also be in other units, such as pixels per meter.
Inherited from default::ThumbRes if not defined or if empty.