Sign Instance
GET /data/api/signs/123/?format=api
https://labasi.acdh.oeaw.ac.at/data/api/signs/123/?format=api", "sign_name": "ŠID", "abz_number": "314 (167)", "meszl_number": "485", "image_1": "https://labasi.acdh.oeaw.ac.at/media/sign_img/sign_314.jpg", "image_2": null }{ "url": "