M

Mainline
	Synonym:
	Definition:   That portion of a pipeline system used for the long 
                      distance transmission of gas.  Gas received "into the 
                      mainline" has been gathered, fully processed and should
                      be of homogeneous composition.
Mainline Quality
	Synonym:      Pipeline Quality
	Definition:   Gas which meets the delivery requirements of the 
                      pipeline with regard to impurities, water content, Btu 
                      content and other physical attributes as specified in 
                      the pipeline's tariff.
Make-Up Gas
	Synonym:
	Definition:   Gas taken under a make-up provision of a take-or-pay 
                      contract that allows the purchaser to receive supplies 
                      that were paid for, but not taken, in previous contract
                      periods.
Marginal Cost
	Synonym:
	Definition:   The added cost the utility incurs by adding an 
                      additional increment of capacity.  "Short term" in this
                      connection usually refers to future periods too close to
                      allow significant construction, usually five years or 
                      less.
Marketable Natural Gas
	Synonym:
	Definition:   Gas that is available for sale for direct consumption as
                      a domestic, commercial or industrial fuel, or as an 
                      industrial raw material, whether it occurs naturally or
                      results from the processing of Raw Natural Gas.  Natural
                      gas which meets specifications for end-use; i.e., has 
                      undergone any necessary processing to remove impurities
                      and by-products.
Marketer
	Synonym:
	Definition:   An individual or company that acts as a middleman 
                      between a seller and a buyer, and as distinct from a 
                      broker, takes title to (purchases) the gas supply.  
                      Often marketers will arrange for any of several 
                      different services for a customer, in order to provide 
                      a complete energy package.
Market Out
	Synonym:
	Definition:   A clause in a natural gas sales contract that allows the
                      purchaser to lower the purchase price or terminate 
                      service in response to market conditions.
Maximum Daily Quantity
	Synonym:      Max Day
	Definition:   The greatest quantity of gas to be received and/or 
                      delivered in a twenty-four hour period by a transporting
                      pipeline on behalf of a shipper, or by a gas seller to a
                      gas buyer, under terms defined in a contract.
Maximum and Minimum Rates
	Synonym:
	Definition:   The most and least that an interstate pipeline can 
                      charge for self-implementing transportation or sales 
                      service.
Maximum Lawful Ceiling Price
	See Ceiling Price
MCF
	Synonym:
	Definition:   A unit of volume equal to a thousand cubic feet; an Mcf
                      of natural gas is generally measured at a pressure of 
                      14.73 PSIA and a temperature of 60 degrees Fahrenheit or
                      other pre-established standard conditions.
Megajoule
	Synonym:      Energy content, heat content, heating value
	Definition:   1 million joules.  Used to express metric heat content
                      by the term megajoule/cubic metre (MJ/m3)
		      1 MJ = 948.2133 BTU		1 Therm = 105.4615 MJ
		      Joules x 106
Merchant Function
	Synonym:
	Definition:   The traditional interstate pipeline role of purchasing
                      gas from producers for resale to captive LDC customers,
                      now largely abandoned due to deregulation and the 
                      resulting proliferation of direct sales.  Also used to 
                      describe LDC to end user relationship.
Minimum Bill
	Synonym:
	Definition:   A clause in a rate schedule that provides for a minimum
                      rate to be paid by the customer, whether the customer 
                      takes the gas or not.
MMBTU
	Synonym:
	Definition:   A unit of heat equal to one million British thermal 
                      units.
MMCF
	Synonym:
	Definition:   A unit of volume equal to one million cubic feet.

Modified Fixed Variable Classification/Tolls
	Synonym:
	Definition:   Similar to Full Fixed-Variable except part of the fixed
                      costs (return on equity and income taxes) are classified
                      as commodity toll related costs instead of demand toll
                      related costs.