Proficiency Testing Scheme

How to read the scheme number

Examples:

• No. PTS 26/03-T-1 - PT scheme of PTS Bulgaria within the scope of accreditation, started in March 2026, the first testing scheme in that month;
• No. ILC 26/10-NA-T-1 - interlaboratory comparison outside the scope of accreditation, started in October 2026, the first testing comparison in that month.

Meaning of the parts of the number:

• PTS - proficiency testing (PT) scheme of the PT provider PTS Bulgaria;
• ILC - interlaboratory comparison other than proficiency testing, under clause 7.7.2 b) of ISO/IEC 17025:2017. It allows a laboratory to compare its results with those of other laboratories and to monitor its performance;
• 26/03 - year and month in which the scheme starts;
• NA (Not Accredited) - the scheme is outside the scope of accreditation and is carried out only in Bulgaria;
• T, S, C - laboratory activity: T - testing, S - sampling, C - calibration;
• 1 - sequence number of the scheme for the same activity in the same month.

Earlier interlaboratory comparisons outside the scope of accreditation are numbered like No. PTS 25/08-NA-1.