MH - Monitor Obstruction
------------------------

The type of obstruction for a monitor with restricted air flow is described by using the MH transaction.


Rules
^^^^^

A Monitor Obstruction record may not be created if the unrestricted air flow indicator for the monitor (State Code, County Code, Site ID, Parameter, POC) is "Y".

A Monitor Obstruction record is required if the unrestricted air flow indicator for the monitor (State Code, County Code, Site ID, Parameter, POC) is "N" or "W".

Examples:

.. code-block:: text
   :caption: MH transaction in default mode

   MH|I|06|073|1201|88101|2|CLIFFS|SSW|627.64|413.31

.. code-block:: text
   :caption: MH transaction in Tribal mode

   MH|I|TT|434|0007|11101|1|BUILDINGS|W|4|2



Format
^^^^^^

.. list-table:: MH - Monitor Obstruction transaction format
   :widths: 1 5 15 4 3 1
   :header-rows: 1


   * - Seq.
     - Name
     - Description
     - Formatting Rules
     - Required
     - Key
   * - 1
     - `Transaction Type <Transaction%20Type.html>`_
     - Monitor Obstruction Info transaction identifier.
     - Must = MH
     - Always
     - 
   * - 2
     - `Action Indicator <Action%20Indicator%20for%20Transaction.html>`_
     - Indicator for Insert, Update, or Delete action.
     - Must = I, U, or D
     - Always
     - 
   * - 3
     - `State Code / Tribal Indicator <State%20Code.html>`_
     - The FIPS state code of the monitor, or "TT" to indicate that the next field on the transaction is a Tribal code.
     - Must exist in STATES Reference Table or be 'TT' for Tribal Site
     - Always
     - Y
   * - 4
     - `County Code / Tribal Code <County%20Code.html>`_
     - The FIPS County Code of the site.  If the previous field on the transaction contains "TT", then the Tribal Code of the site.
     - Must exist in COUNTIES (for state) or TRIBAL_AREAS Reference table
     - Always
     - Y
   * - 5
     - `Site Number <Site%20Number.html>`_
     - Four digit number to uniquely identify site in county and/or tribe.
     - Must exist in SITES table with {State Code, county Code} or Tribal Code
     - Always
     - Y
   * - 6
     - `Parameter Code <Parameter%20Code.html>`_
     - The AQS parameter code assigned to the monitor in AQS.
     - Must exist in PARAMETERS reference table.
     - Always
     - Y
   * - 7
     - `POC <POC.html>`_
     - Parameter Occurrence Code:  One or two digit number identifying a specific monitor for a parameter at the site.  
     - Must exist in MONITOR table for non-Insert actions.
     - Always
     - Y
   * - 8
     - `Probe Obstruction Type <Probe%20Obstruction%20Type.html>`_
     - The type of obstruction responsible for the restricted air flow of a monitor.
     - Must exist in PROBE OBSTRUCTION TYPES reference table.
     - Always
     - Y
   * - 9
     - `Direction from Monitor to Probe Obstruction <Probe%20Obstruction%20Direction.html>`_
     - The true direction from the monitor to the obstruction.
     - Must exist in COMPASS SECTORS reference table.
     - Always
     - 
   * - 10
     - `Distance from Monitor to Probe Obstruction <Probe%20Obstruction%20Distance.html>`_
     - The distance, in meters, between the probe and obstruction.
     - Decimal.
     - Always
     - 
   * - 11
     - `Probe Obstruction Height <Probe%20Obstruction%20Height.html>`_
     - The height, in meters, of the top of the obstruction above the probe.
     - Decimal.
     - Always
     -