The network code on interoperability aligns the complex technical procedures used by network operators within the EU, and possibly with network operators in the Energy Community and other countries neighbouring the EU. Article 7, Measurement principles for gas quantity and quality. In addition to interconnection points, Article 17 shall apply to other points on transmission network where the gas quality is measured. Article 18 shall apply to transmission systems. This Regulation may also apply at entry points from and exit points to third countries, subject to the decision of the national authorities

Since hydrogen is not mentioned there a reference cann’t be given. It is a missing provision so far.

Directive 2009/73/EC establishes common rules for the transmission, distribution, supply and storage of natural gas.
Its provisions and obligations apply to Hydrogen Gas by virtue of Article 1 (2), which states that the rules established by this Directive for natural gas, including LNG, shall also apply in a non–discriminatory way to biogas and gas from biomass or other types of gas in so far as such gases can technically and safely be injected into, and transported through, the natural gas system.

Other relevant provisions for the injection of hydrogen at transmission level are contained in Article 42 “Regulatory regime for cross–border issues” and Article 43 “Compliance with the guidelines"

Article 8 “Technical rules”, Article 25 “Tasks of a distribution system operator”; Article 28 “Closed distribution systems”
Article 41 “Duties and powers of the regulatory authorities”
Article 35 “Refusal of access”; Article 8 “Technical rules”; ”

Regulation 715/2009 sets non-discriminatory rules for access conditions to (a) natural gas transmission systems; (b) LNG facilities and storage facilities taking into account the special characteristics of national and regional markets

To achieve this, it sets harmonised principles for tariffs, or the methodologies underlying their calculation, for access to the network, but not to storage facilities, the establishment of third-party access services and harmonised principles for capacity-allocation and congestion-management, the determination of transparency requirements, balancing rules and imbalance charges, and the facilitation of capacity trading.

This Regulation establishes an Agency for the Cooperation of Energy Regulators in order to assist the regulatory authorities in various regulatory tasks.

Article 8 sets the Agency’s “Tasks as regards terms and conditions for access to and operational security of cross border infrastructure” thus making it a relevant stakeholder in the regulatory landscape of hydrogen gas transmission and distribution.

Regulation 2015/703 establishes a network code which sets out rules regarding interoperability and data exchange as well as harmonised rules for the operation of gas transmission systems.

The network code on interoperability aligns the complex technical procedures used by network operators within the EU, and possibly with network operators in the Energy Community and other countries neighbouring the EU. This Regulation may also apply at entry points from and exit points to third countries, subject to the decision of the national authorities.