Unrestricted Air Flow Indicator
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Description
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An indicator of whether the flow of air in the vicinity of the monitor's probe is unrestricted by physical obstructions.  

Valid values: 

* Y : Yes - no restriction
* N : No - flow is restricted by obsstructions
* W : Waiver - Flow is restricted unavoidably, and the probe location has been approved by the EPA

Business Rules
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An unrestricted air flow indicator value is valid if it is Y (for yes), N (for no), or W (for waiver). 

If the value entered is N, transaction MH is required to enter monitor obstruction information.