PG, please visit this wiki page Numbered Musical Notation for detailed explanation and samples. Many chinese hymnals are printed in this format.
This notation system is akin to Nashville system for Chords and hence is great for computerised classification of songs in BB.
Quote:

Here is quote from the wiki:
An index using the numbered notation allows us to find a song if we remember the tune but not the name. To appreciate that, we can look at an example. A children's song book may have an index like this:

|1· 1· |1 23· | Row, row, row your boat

|1 1 5 5 |6 6 5 - | Twinkle, twinkle little star

|1 2 3 1 |1 2 3 1 | Frere Jacques

...
Compared to the standard notation, the numbered notation is very compact for just the melody line. It is even possible to transcribe music in between the lines of text. Transcribing harmony can be done by vertically stacking the notes, but the advantage of compactness decreases as the harmony becomes more complex. The standard notation, with its graphical notation, is better in representing the duration and timing among multiple notes.


BB with this feature could be a hit in the huge China market.