This libretto of the opera Tosca by Giacomo Puccini has been designed and typeset to increase ease of use and legibility for the singers.
The left page is the original Italian, with a translation on the right.
Each character has its own column; so singers can easily follow their part. While also seeing the parts of those singing around them.
The timing between parts is one of the key elements within this music. This gives a clear visual of the timing throughout the opera. Listen to the drama.