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About the OIML
# Introduction and Structures  
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# Headquarters (BIML)  
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# Organizations in Liaison  
# Memoranda of Understanding (MoU)  
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# Becoming an OIML Member  

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# Committee Drafts  
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# Technical Liaisons  
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OIML Systems
# Introduction  
# Mutual Acceptance Arrangement - MAA  
# Registered Certificates  

National Regulations
# Inquiry results: OIML R  

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# OIML Meetings  
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# OIML Seminars  
# Events of Interest  

Restricted Access
# Members' Access  
# Presidential Council  

The OIML Basic Certificate System and the OIML MAA

The OIML Basic Certificate System

The OIML Basic Certificate System for Measuring Instruments was introduced in 1991 to facilitate administrative procedures and lower the costs associated with the international trade of measuring instruments subject to legal requirements. The System, which was initially called "OIML Certificate System", is now called the "OIML Basic Certificate System". The aim is for "OIML Basic Certificates of Conformity" to be clearly distinguished from "OIML MAA Certificates".

The System provides the possibility for manufacturers to obtain an OIML Basic Certificate and an OIML Basic Type Evaluation Report (called "Test Report" in the appropriate OIML Recommendations) indicating that a given instrument type complies with the requirements of the relevant OIML International Recommendation.

Certificates are issued by those OIML Member States that have established one or several Issuing Authorities responsible for processing applications by manufacturers wishing to have their instrument types certified.

Basic OIML Certificates are accepted by national metrology services on a voluntary basis, and as the climate for mutual confidence and recognition of test results develops between OIML Members, the OIML Basic Certificate System serves to simplify the type approval process for manufacturers and metrology authorities by eliminating costly duplication of application and test procedures.

An OIML Recommendation can automatically be included within the System as soon as all the parts - including the Evaluation Report Format - have been published. Consequently, OIML Issuing Authorities may issue OIML Certificates for the relevant category from the date on which the Evaluation Report Format was published; this date is now given in the column entitled "Uploaded" on the Publications Page.

Additionally, when a new version of an OIML Recommendation is published, the earlier version may be maintained in the OIML Basic Certificate System, together with the new version. This means that OIML Issuing Authorities may continue to issue OIML Certificates for the previous version of the Recommendation, despite the fact that the latter is listed in the "Superseded" section of the Publications catalog.

Other information on the System, particularly concerning the rules and conditions for the application, issue, and use of OIML Certificates, may be found in OIML Publication B 3 OIML Certificate System for Measuring Instruments (Edition 2011) which may be downloaded from the Publications page.


In addition to the existing OIML Basic Certificate System, the OIML has developed a Mutual Acceptance Arrangement (MAA) which is related to OIML Type Evaluations. This Arrangement - and its framework - are defined in OIML B 10 (Edition 2011).

The OIML MAA is an additional tool to the OIML Basic Certificate System in particular to increase the existing mutual confidence through the System. It is still a voluntary system but with the following specific aspects:

  • Increase in confidence by setting up an evaluation of the Testing Laboratories involved in type testing - this evaluation is based on the international standard ISO/IEC 17025 and may be carried out either by accreditation or by peer assessments;
  • Assistance to Member States who do not have their own test facilities and the possibility for national legal metrology bodies to be able to rely on the facilities and competences of other countries' bodies, especially in cases where they do not themselves possess such facilities at national level;
  • Possibility to take into account (in a Declaration of Mutual Confidence, or DoMC) additional national requirements (to those of the relevant OIML Recommendation).

The aim of the MAA is for the participants to accept and utilize MAA Evaluation Reports validated by an OIML MAA Certificate of Conformity. To this end, participants in the MAA are either Issuing Participants or Utilizing Participants.

For manufacturers, it avoids duplication of tests for type approval in different countries and gives them the knowledge, at the beginning of the evaluation process, of the additional national requirements requested in the various countries in which they will apply for type approval.

Participants (Issuing and Utilizing) declare their participation by signing a Declaration of Mutual Confidence (Signed DoMCs).

Detailed information on the MAA is available under the MAA section.