Page 1 of Engel (Bosse/Partitura) has a boxed VERSE 1 label in the left
margin at the same rows as the preceding system's bass lyric line — ink
on both sides of the page throughout the band, so no horizontal line
separates them. The label belongs to system 2, the lyrics to system 1.
A cut is therefore a polyline spanning the page, two points being the
ordinary straight case. A slice bounded by a non-straight cut is not
rectangular: its image is the region's bounding box with everything
outside made transparent, which composites invisibly on the viewer's
sheet. Masking paints transparency, never white.
Esa Kataja
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