Day 195/365 Let's talking about a music theory today. Nowdays there are two types of notation for notes. UT queant laxis REsonare fibris MIra gestorum FAmuli tuorum, SOLve polluti LAbii reatum. The names of the six notes were introduced by Guido d'Arezzo. ( later UT would be changed into Do ,it was more convenient for singing.)then they added Si, it's an abbreviation from «Sancte Ioannes». Another common system of notation for notes is alphabetic: notes from C to H are denoted by letters of the Latin alphabet. This is a German system,where note SI denoted by letters H. Almost all European countries, except those, where English language is main ,using German system of notation. Letter B there means flat-si. There is also an English notation system, where the note SI denoted by letters B. This system is more popular in the USA,UK, part of people use it in Switzerland and Holland. In Russia and China we use the same system of notation, we say : Do-Re-Mi-Fa-Sol-La-Si.