Hold lines in figured bass are as far as I can discover not so well documentated.
A hold line in the lowest figure is easy but in middele or upper figures not so easy or unpredictable (for me).
In those cases I have the impression that writin the full harmony and afterwards replacing it with the hold lines is succesful. Look at my example.
Hold lines, to the best of my knowledge, should show whenever a figure extends (has duration over) either a change in the bass note or stays the same while other figures change. There are options for when hold lines should appear in Engrave > Engraving Options > Figured Bass > Design.
No, hold lines are more an exception than a rule. But when they are you it is indeed as described above.
For example Marais only writes the absolute necessary figures, Bach preferres to write out the complete figures all the time (generally), Telemann is very fond of lines: quicker!
Apologies, I meant “should show” in the context of Dorico, as in Dorico will automatically show them in those contexts - that wasn’t a notation judgement!
should be
But when they are there
