vscode-extension-samples/custom-data-sample/css.css-data.json

{
  "version": 1.1,
  "properties": [{
    "name": "my-size",
    "description": "Compiles down to `width` and `height`. See details at https://github.com/postcss/postcss-size",
    "references": [
      {
        "name": "GitHub",
        "url": "https://github.com/postcss/postcss-size"
      }
    ]
  }],
  "pseudoClasses": [{
    "name": ":my-link",
    "description": ":any-link pseudo class. See details at https://preset-env.cssdb.org/features#any-link-pseudo-class"
  }]
}