how to update managed metadata fields using rest?

I am using rest to post resources in Sharepoint and I can insert my files without problems. However, when I tried to update the metadata fields even using the unique identifier of the term I want to introduce does not work.

I am using nodejs from the server side, so the client side possible libraries are not applicable.

Below I send part of the code I use to update my data.

    var urlT = url + "/_api/web/lists/getbytitle('Project%20Icon%20Library')/items(1)";

    httpntlm.post({
    url: urlT,
    username: config.sharepoint.username,
    password: config.sharepoint.password,
    headers:
      {
        "accept": "application/json;odata=verbose",
        "content-type":"application/json;odata=verbose",
        "IF-MATCH": "*",
        "X-HTTP-Method": "MERGE",
      },
    requestDigest:XrequestDigest,
    data:data,
  }