BL—Analyzer reading at the specified LDL test concentration for the LDL test.

BZ—analyzer reading at 0 concentration for the LDL test.

DM—Digital meter.

Cmax—Maximum analyzer reading during the 12ZD test period.

Cmin—Minimum analyzer reading during the 12ZD test period.

i—Subscript indicating the i-th quantity in a series.

IE—Interference equivalent.

L1—First analyzer zero reading for the 24ZD test.

L2—Second analyzer zero reading for the 24ZD test.

n—Subscript indicating the test day number.

P—Analyzer reading for the span drift and precision tests.

Pi—The i-th analyzer reading for the span drift and precision tests.

P20—Precision at 20 percent of URL.

P80—Precision at 80 percent of URL.

ppb—Parts per billion of pollutant gas (usually in air), by volume.

ppm—Parts per million of pollutant gas (usually in air), by volume.

R—Analyzer reading of pollutant alone for the IE test.

R1—Analyzer reading with interferent added for the IE test.

ri—the i-th analyzer or DM reading for the noise test.

S—Standard deviation of the noise test readings.

S0—Noise value (S) measured at 0 concentration.

S80—Noise value (S) measured at 80 percent of the URL.

Sn—Average of P7 .  .  . P12 for the n-th test day of the SD test.

S'n—Adjusted span reading on the n-th test day.

SD—Span drift

URL—Upper range limit of the analyzer's measurement range.

Z—Average of L1 and L2 readings for the 24ZD test.

Zn—Average of L1 and L2 readings on the n-th test day for the 24ZD test.

Z'n—Adjusted analyzer zero reading on the n-the test day for the 24ZD test.

ZD—Zero drift.

12ZD—12-hour zero drift.

24ZD—24-hour zero drift.