But, there is a case in notes sheets, when no size is been told. This case in notes grammar is - describing the tone of the hole song.
Example notes sheet without size clarification:
Sometimes it is possible to see the song, which is that kind of short, like on the picture below:
That kind of writing a song down - is a transfering the tone of the hole song. This short notes sheet means - you must stretch this notes, on any length you want. This small amount of notes on the sheet means you should play 1 minute long, a tone E for example, then you must play 2 minutes tone A, and so on. So, the length of the song from this short notes sheet could be like 10 minutes.