Which data should be made public in the city guide

Article 8 of the Zoning Law No. 3194 explicitly provides that zoning plans are public and that ensuring this openness is the duty of the relevant administrations. The same article requires that approved plans be announced simultaneously, for a period of one month, both at the notice locations determined by the municipal mayor's office and on the relevant administrations' websites.

The provisions of the article, as amended in 2020 by Law No. 7221, have also made electronic publication part of this obligation. Plans, plan amendments and revisions must be uploaded to the electronic environment created by the Ministry and must receive a Plan Transaction Number. It is also mandatory to produce digitally, and announce electronically, the plans, parcellation plans, building permits and occupancy permits, as well as the orthoimages and other geographic data subject to zoning legislation, and to ensure their integration with the National Geographic Information System Infrastructure. These provisions provide a strong basis for showing zoning information in the city guide.

Layers that are not linked to an individual and that show the location of a public service form the core of the public-facing part of the city guide. For these layers, the main consideration in publication is the accuracy and currency of the data.

• Approved zoning plans, plan notes and plan functions.
• Block and parcel boundaries, together with block and parcel numbers.
• Address information at the level of neighbourhood, avenue, street and door number.
• Service points such as schools, health facilities, neighbourhood administration offices (muhtarlık), sports facilities, parks and duty pharmacies.
• Disaster and emergency assembly areas and evacuation routes.
• The location of ongoing road and infrastructure works and their planned completion date.

Infrastructure lines, the detailed locations of critical facilities and structures sensitive from a security standpoint require separate assessment. It is appropriate to decide whether these layers are made public after obtaining the opinion of the relevant unit and the information security officer.

In practice, the soundest method is to define two separate access levels on the same data infrastructure. In the public-facing portal, only the layers and attributes that have been decided for publication are shown; institutional staff, on the other hand, access more detailed layers to the extent required by their duties. This separation also reduces the risk of inconsistency that arises from keeping the data in two separate copies. A record should be kept of which layer is opened at which level, and this record should be updated whenever the decision changes.

The Personal Data Protection Law No. 6698 (KVKK) defines personal data as any information relating to an identified or identifiable natural person. Although a parcel boundary alone is not considered personal data, a layer becomes personal data when the owner's name, share information, or debt and tax information linked to a person is shown together with the parcel.

Article 1020 of the Turkish Civil Code states that the land registry is open to everyone; however, it provides that the viewing of the register page and documents, or the issuing of a copy of them, may be requested from the land registry officer only by a person who substantiates a legitimate interest. The openness of the registry does not mean that owner information can be published to everyone, without limit, over the internet. The Parcel Inquiry application of the General Directorate of Land Registry and Cadastre reflects this same distinction: the application shows the parcel's location, area and nature, does not allow queries by owner name or national identity number, and directs users to the "My Land Registry Information" screen on e-Devlet (the national e-government portal) for that information.

In its decision of 25 February 2021, numbered 2021/140, the Personal Data Protection Board examined the internet services of municipalities. The Board found applications that allow property and debt information to be queried using a single piece of information, such as the national identity number, to be in breach of the data security obligation under Article 12 of the Law, and required municipalities to move to multi-layered measures such as additional verification, SMS verification or membership. This decision is directly instructive if a personalised query is to be added to the city guide.

The city guide allows data to be displayed on a map. The open data approach goes one step further, aiming to present the same data in a form that others can reuse. On 20 January 2023, the European Commission published its list of high-value datasets, in which it designated geospatial data as one of six thematic categories and required public institutions to make these datasets available for reuse, free of charge, within 16 months.

The practical equivalent of this example for municipalities is as follows: layers shown as publicly accessible in the city guide that do not contain personal data — such as service points, assembly areas or address data — could also be considered for publication as downloadable datasets with a stated licence. Layers containing personal data, however, should be kept outside the scope of open data.

Information shown on the map is perceived by the citizen as official information. Article 8 of the Zoning Law also requires that plans and geographic data be kept up to date; Article 4 of the KVKK lists the accuracy and, where necessary, the currency of personal data as a general principle. For this reason, the responsible unit, the update cycle and the date of the last update should be determined for each layer and shown on the portal wherever possible. It should also be stated explicitly that the zoning information presented on the map is for informational purposes and that, for official transactions, the document issued by the administration is the one that governs.

Accessibility is also part of this responsibility. Article 7 of Law No. 5378 on Persons with Disabilities provides that information services and information and communication technology shall be made accessible for persons with disabilities. In map-based applications, keyboard usability, screen-reader compatibility and result lists that are also accessible as text outside the map should be planned on the basis of the W3C's Web Content Accessibility Guidelines (WCAG 2.2).