MTIA (Medical Transcription Industry Association) along with AHIMA (American Health Information Management Association) recommends a standard unit of measure for medical transcription of patient medical records.
It recommends the visible black character (VBC) measurement standard to be the best document counting method.
What was the purpose of having such a standard? The final goal was to implement a standard for content measurement that the health information management (HIM) practitioners can use to evaluate in-house transcription staff and external transcription service suppliers.
The earlier 65-character line standard (also called as the AAMT line) had previously been a standard industry wide unit of measure for content measurement that includes space bar, shift key, bold, underscore, and other keystrokes.
With this system the cost for the line/character goes beyond just labor as the cost of the technology is bundled along with domain knowledge and human resources.
Thus it became mandatory to develop/choose the best possible Industry standard.
The benefits of having such a standard include ease in maintaining service level agreements, better business relationships and having a better tool for evaluation.
According to The MTIA /AHIMA task force among all the different counting methods like ASCII line, the 65-character line, gross line, gross page, per minute pricing, and visible black character (VBC) measurement standards, VBC is the only counting method that can be easily understood, verified, and replicated by all parties in the medical transcription business processes.
Whenever a transcription document is reviewed for quality what are the principles that establish the quality of the documents?

The transcribed report should be reviewed against the actual dictation.
Reading the report without listening to the dictation does not provide an accurate comparison of the transcription to the dictation.

The review should apply industry-specific standards as provided by current resources and references.
When evaluating style, punctuation, or grammar, The AAMT Book of Style is the industry standard.

The review should encompass attention to risk management issues and the documentation standards of accreditation and healthcare compliance agencies.

Accuracy scores (ratings) should be quantified with the use of a numeric calculation that weights varying degrees of error against the length of the report.
AAMT recommends the following quality goals: 100% accuracy with respect to critical errors; 98% accuracy with respect to major errors; and 98% accuracy with respect to all errors in the report, including minor errors (see below for definitions of "critical," "major," and "minor" errors).

The reviewer (or the review process) should provide timely and consistent feedback to the medical transcriptionist in order to eliminate repetition of errors.

All measurements, standards, and benchmarks should be disclosed to the medical transcriptionist and should be set forth in written guidelines by the healthcare provider or transcription service.