This question is about how to write instruments names on a score.
On the page at:
list the full instrument names and include all instruments. In subsequent systems, use abbreviations for the instrument names (if you only have 1-2 instruments, you can omit instrument names entirely).
I have 2 human voices in my song and a piano (expressed by 2 staves exactly); each of the human voices have exactly one stave. So there are three instruments in total (which are 2 human voices and a piano).
Following the above quote, when the instrument first appear in the music I am labeling it as "Voice 1" as the main voice, "Voice 2" as the background voice, and the other 2 staves as "Piano" where the 2 piano staves are indicated by a curly right bracket (see image).
On following lines, at the beginning of each such line I use the abbreviation "V1", "V2", and "Pno." for "Voice 1", "Voice 2" and "Piano" respectively.
I have sketched out a representative sheet music in the image to describe the above notation:
My question is: Am I writing the instruments in a standard professional way in my sheet music?
I expect this is an easy question for someone with more experience than me—but notating music is a learning process for me.
Update: after reading the answer I think that the following, sketched below, would be a good way to do the notation. Showing Voice1 (main voice), Voice2 (backing voice), Piano at the start if the first line of bars. The simply using the square bracket for the two voice staves and the curly bracket for the two piano staves for the remainder of the sheet music and where each line of new bars start. I think using this notation it is clear what is meant-it is for a pop song,on a single piano,with backing vocal where the backing vocals has different words to the main vocals-though I think the same notation would apply for the hypothetical scenario of if the words of the two voices was the same words.