Copies just one field from all species listed in the source database (DB) on the left side, to the corresponding species (i.e. the species with same ID aka 'name'-entry) in the target DB on the right side.
If no such corresponding species exists, it will be created.
Normally this function overwrites existings target fields w/o any warning.
If the 'Append data?' toggle is checked, the data of the source field will be appended to existing target fields (separated by a space). Appending only works for string fields.