Dear it rains inside,
I can add a little background to Tony’s interesting post.
I think you will appreciate that any FS methodology invoving risk assessment / risk probabilities such as HACCP is inevitably going to be subjective as far as (a) determining hazards which need to be controlled, eg the “significant” ones and then (b) selecting appropriate control measures for the hazards chosen.
Codex/NACMCF published summaries of their, developed, methodologies in the 1990s which remain the basis of most “traditional” HACCP methods.
ISO developed/presented a modified approach in ISO22000-2005 focusing (with respect to HACCP) on categorising control measures into Prerequisites / CCPs (using the term loosely) / OPRPs. The control measure/function/program OPRP was introduced to allow/manage for certain hazards which were not readily handled by the, then, current HACCP procedures such as referred above.
Defining/selecting OPRPs was an immediate source of controversy in FS-HACCP circles and was attempted to be further rationalised by ISO via their near-simultaneous release of the 22004 technical “Guide”. This did explain/simplify certain aspects but unfotunately blurred over specific expectations for identifying OPRPs so that the arguments continued to reverberate. Sadly, AFAIK, ISO never published any “worked examples based on their standard, presumably from fear of creating a precedent over subjectivity. Conceptual/practical debates over the correct/best methods of interpreting/finding OPRPs continue up to today.
Based on threads in this forum, FS Auditors from the beginning of ISO 22000 have apparently felt obliged to accept any procedure based on a “logical” and “validatable” interpretation of the ISO/FSSC text which yielded an effective mixture of PRPs / CCPs / OPRPs, ie gave a satisfactory result with respect to consumer Food Safety (there are likely to be some geographical caveats in the preceding comment). The later release of the ISO list of (preferred) Prerequisites has considerably aided the PRP segment of ISO-FSSC 22000.
In practice the "HACCP" methodologies published/utilised for ISO-FSSC range from short to lengthy, very simple to highly intricate. And a similar comment regarding the eventual numbers of CCPs/OPRPs involved. History tends to repeats itself ?.
Rgds / Charles.C