I’m studying Tchaikovsky’s Symphony No. 6 and have come across two lines which look like they are intended to save paper in just showing the musical lines that are playing?
They are everywhere, the next page too.
What’s the proper name for these? And are they for what I had thought initially? To prevent musical instruments not playing just displaying empty staff lines with rests? If you look at the example above it’s just the Viola and Cello.
I have found an answer in the book "Behind Bars" by Elaine Gould. She writes (p.521):
A pair of thick diagonal lines, known as system dividers or separation marks, divides off two or more systems of orchestral (or ensemble) music on a page. [...] Where systems can be well separated, the dividers may be placed on the left hand side of the page only; where systems are very close together, it is visually helpful to add them on both sides of the page.