The ‘station numbering system’s’ purpose is to show railway stations with a letter corresponding to the subway line and a number corresponding to the station, both with the railway line's unique colour.

The left image represents Asakusa Station, which is on the Ginza Line.

The ring color and the letter ‘G’ show that this station is on the ‘Ginza Line’, and the number (19) indicates that it’s Asakusa Station.

Almost all the railway companies in Japan have introduced this system for visitors (who find it challenging to read station names in Japanese). Even if the station names are written in Romaji, which was developed to describe the sound of Japanese words in the Roman alphabet, the station names (in Romaji) are hard to pronounce for Japan’s visitors. On the other hand, ‘station numbering’ is useful for visitors, as they do not need to read the difficult Romaji to find their destinations.

An ‘entrance’ represents an entrance at the ground level that leads to a ticket gate. Conversely, ‘a ticket gate’ is a gate that allows access to a platform for a train line.

Reference:"How to use" page has Glossary of transfer page underneath.

Metro's Gnome Tokyo does not include all the train information on the map. Therefore, the excluded lines and stations are shown in the ‘Other transfer lines’ section. Examples of ‘other transfer lines’ are listed in the ‘Lists of lines and stations’ section.

‘JR’ is an alphabetical abbreviation for the ‘Japan Railway Service Company’. Japanese people call this company ‘JR’. JR East is the biggest of the JR group companies, and it manages major lines, such as Yamanote (JY) and Chuo (JC) in Tokyo. Lines with station numbers that start with ‘J’ are under the management of JR companies.

You will not be able to see your current location on the map if you’re outside Tokyo. If you are far from Tokyo (like 800 km, for example), Metro's Gnome Tokyo will show Tokyo Station at the centre of the map instead of your current location. However, you can still see relevant station information.