Harmonization Document (HD)


Harmonization Documents (HD) are a CENELEC only deliverable developed in IEC and adopted in CENELEC along with the provisions of the Frankfurt Agreement. HDs are normative documents made available in the three official languages.

During the elaboration and whole lifetime of the Harmonization Document, standstill applies.

A-deviations and special national conditions (SNCs) are applicable to HDs.

HD can be harmonized in support of European Regulations and resulting Standardization requests.


The preparation, update and the review of an HD follows the same procedure as given for an EN, including the development of Amendments.


Members are able to publish national standards equivalent in technical content to an HD (see CEN-CENELEC Internal Regulations - Part 2, clause 11.6). Those national standards shall neither contradict, nor alter provisions, nor add additional requirements to the HD.

When developing such a national standard the Vilamoura process applies (see CENELEC Guide 8 'The Vilamoura notification procedure for new national work and for the revision of national standards').


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A European Standard (EN), in principle, needs to be identically adopted at national level by all CENELEC members whereas the HDs only need to be announced. In both cases national conflicting standards need to be withdrawn.

ENs and HDs are made available in the three official CENELEC languages (English, German and French). HDs have to be announced at national level (and conflicting national standards shall be withdrawn). In addition, HDs can be used as a basis for the development of national standard(s) equivalent in technical content.


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