Honeywell CM4 Technical Handbook page 199

CM4 Four-Point Continuous Monitor
nvo00AlmL is equal to the highest alarm level on any point. This is
provided to permit less-tedious binding of large networks.
The gas concentration is reported in Nvo0xConc for each point x. This
is a four-byte floating-point number in parts per million in accordance
with LonMark standards.
Nvo0xFlow reports the sample flow for each point x. This is in cc/
minute as a 16-bit integer. Note that this number is rarely needed as
the CM4 checks for low flow internally.
The frequency of data transmission varies according to the value of
data contained in order to conserve network bandwidth while providing
quick notification of problems. In general, zero-valued data is only
transmitted every 50 seconds. Non-zero data is transmitted every
second. Frequent transmission of Nvo00Status will occur if any alarm
or any fault is active.
CM4 Technical Manual G-10