Many sites utilize tags in one form or another: On the *booru sites such as danbooru tags are used to express all relations and features of an image. Facebook and Twitter allow you to add hashtags to posts as searchable keywords. Amazon allows users to tag products. Tags have multiple uses, and conventions vary slightly from site to site. It’s not always clear how they used be used and for what. Here I try to explain how they’re intended to be used on VocaDB, and generally what can be expressed with tags.
Most of the information on VocaDB is as objective as possible, meaning it should be accurate and true, regardless of whom you ask. Some things, however, can be difficult to define. The tagging system on VocaDB was originally added to be able to associate songs and albums with genres. Genres are a good example of a concept that can be difficult to define: most people are able to tell whether a particular song is rock, but is it pop rock, hard rock, glam rock, punk rock or progressive rock? Multiple genres may apply to a single song. This is why genre isn’t a single field and is based on voting. Everyone is able to suggest a list of genres. If someone else agrees with some of those suggestions, but possibly not all of them, they can add votes to the genres they agree with. The genres that have received the most votes will appear first. In other words, for things where we can’t trust that a single person’s opinion is correct, we have democracy.
While genres are probably the most important category of tags, they’re certainly not the only one. Entries have a limited number of predefined fields, but tags allow you to go beyond that. Tags can be used to define associated copyrights, such as an anime series which a song is from. They can also be used to define themes, languages and MMD characters. The list is endless. There are some guidelines for good tags though.
As already mentioned in the site’s guidelines section, tags should be fairly objective to be useful. But what is objective? Certain things like “Christmas” for Christmas-themes songs is very objective and clear. Usually there’s no argument whether a song is about Christmas or not. But can “cute” be objective? Would others agree with you that a particular song/PV is “cute”? Objective things are something that you can measure or prove. In this sense, some features of cuteness can in fact be measured. There’s a lot of gray area of course, and we’ve been quite lenient regarding this, meaning if something can potentially be objective we’d allow it as a tag. For clearly subjective concepts such as “beautiful” it’s better to create a personal song list rather than use a tag, because it’s unlikely that others would share your sense of beauty.
You can see it this way: tags can be any meaningful things you can identify. They help people to discover and remember songs. If the lyrics and/or the PV is about airplanes, it’s ok to tag the song with “airplane”. If the PV features a house, you can add the “house” tag, although unless the house is in any meaningful role in the PV, it’s probably not very useful.
When tagging entries it’s usually a good idea to check the tag description first if you’re unsure, so that you’re not using the tag in a way that wasn’t intended.
VocaDB tags compared to other sites and when not to use tags on VocaDB
As mentioned, some sites such as danbooru use tags for almost anything. Most importantly, they use tags for artists, while VocaDB already offers a more specialized way of linking songs and albums to artists. The general guideline on VocaDB has been not to use tags for things that are already expressed by other features. Tagging songs with artist tags would be redundant because you can already search for artists separately and then see a list of their songs.
There’s an exception to this rule though: sometimes tags can be used to augment those specialized fields. The primary category of an album or song is determined by a specialized field, but if the entry fits into multiple categories you can use tags for those secondary categories. For example, original instrumental songs. Original song type overrides instrumental, meaning that if the song is original, that type should be used instead of the instrumental song type, even if the song is an instrumental. Instead, you should tag the song as “instrumental”, to indicate that the song is in fact an instrumental (the instrumental song type should only be used for instrumental versions of originals).
Sometimes this isn’t clear either: people have added tags for things that are indirectly expressed by other features on the site. For example, the “UTAU” tag for songs when the vocals are provided by an UTAU, or the *lyrics tags for songs with lyrics of different languages. These are slightly controversial, considering the information is already available in the system. It would be perfectly possible to have a feature in the song search which would allow you to search for songs with UTAU vocals or songs with lyrics, without any manual tagging. That’s why I’d recommend against using tags for things that are indirectly expressed by other features on the site. If you feel that a song search for UTAU songs would be useful, please request that as a feature, and if enough people agree, we can implement it properly, in a way that requires less manual maintenance than using tags for it.
The range of available characters in tag names is limited at the moment. Tag names can only contain alphanumeric characters (both upper and lowercase) as well as hyphens and underscores. We might allow more character ranges in the future, especially Japanese characters, if needed. At the moment, consider the following guidelines when deciding a name for a tag that doesn’t already exist. Use common English language rules for casing, meaning only proper nouns start with a capital letter, otherwise the tag name should start with a lowercase letter. For example, Final_Fantasy (proper noun) vs. progressive_rock. Abbreviations such as “RPG” should also be written in capital letters of course. Separate words with underscores.
Future developments: tag hierarchies
VocaDB allows you to group tags into categories to make them easier to find. For example, all genre tags should be grouped under “Genres”. However, the number of tags has grown so much that a single level of grouping doesn’t seem to be enough anymore. Users have expressed the need for assigning tags into hierarchies: for example, the “progressive_trance” tag could be grouped under “trance”, which in turn could be under “electronic”. While useful, there’s still multiple open questions regarding the implementation, for example whether tags should be allowed to exist in multiple branches of the hierarchy. At this point I’m reluctant to add new features until they’ve been properly thought out, otherwise we’d risk complicating the site unnecessarily.