Each point's label from one source. The same label given twice is fine; two different labels from the same source for one point throw, naming both lines, because either choice would be a guess.
The parsed label lines.
The label source, such as construction.
construction
The label file's name, for messages.
Each point's label from one source. The same label given twice is fine; two different labels from the same source for one point throw, naming both lines, because either choice would be a guess.