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 12 ZD test period.
Cmin -Minimum analyzer reading during the 12 ZD test period.
i -Subscript indicating the i -th quantity in a series.
IE -Interference equivalent.
L1 -First analyzer zero reading for the 24 ZD test.
L2 -Second analyzer zero reading for the 24 ZD 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.
12 ZD -12-hour zero drift.
24 ZD -24-hour zero drift.
40C.F.R. 53 app Table B-5 to Subpart B of Part 53