Static Textures

Static textures are located in the signs/static folder of your pack.

To add a static texture, simply put your texture file in the signs/static folder.

By default, your texture will not have a category (and show up under "Uncategorized"). It will also not have any defined colors. To define colors for the texture, you need to attach a static texture definition to your texture.

Static Texture Definition

To add a static texture definition, create a json file with the same name as your texture file, but replace .png with .static.json.

A static texture definition can define custom colors:

{
  "colors": {
    "foreground": "white",
    "custom_color": "#4287f5"
    // ...
  }
}

Adding a Category

To create a new category, all you need is a folder and a _category.json file inside that folder. All static textures in that folder (but not its subdirectories) will then belong to that category.

And then give a name to your category in the _category.json file:

{
  "name": "My Category"
}

You can also define a default texture definition inside of _category.json, so that you don't need to create a .static.json file for every texture in that category.

{
  "name": "My Category",
  "default": { 
    "colors": {
      "foreground": "white"
    }
  }
}

References

Static Texture Definition (.static.json)

Category Definition (_category.json)