What does "NRM" stand for? "CLW"? Etc. etc.

Loco, coach, and wagon manufacturers whose products have been used in India
ABB	ASEA Brown-Boveri, Switzerland
ALCO	American Locomotive Co., Schenectady, NY, USA
BBUNL	Bharat Bhari Udyog Nigam, Ltd.
BEML	Bharat Earth Movers Limited
BHEL	Bharat Heavy Electricals Limited
BLW	Baldwin Locomotive Works, USA
BP	Beyer Peacock, Manchester
BSCL	Burn Standard Co., Ltd.
BTH	British Thomson Houston
BWEL	Bharat Wagon and Engineering Co., Ltd.
CLW	Chittaranjan Loco Works,
also	Canadian Locomotive Works (now Bombardier)
DLW	Diesel Loco Works, Varanasi
EBW	E. B. Wilson
EE	English Electric
EMD	General Motors' Electro-Motive Division, USA
GEC	General Electric Corporation, UK
GM	General Motors, USA
GMD	General Motors Diesel, Canada
HL	Hawthorn-Leslie, Newcastle-upon-Tyne, UK
ICF	Integral Coach Factory, Perambur
ISW	Indian Standard Wagon Works, Satna
KS	Kerr Stuart, Stoke-on-Trent, UK
LHB	Linke Hoffman Busch GmbH, Germany
MLW	Montreal Locomotive Works
MV	Metropolitan Vickers
NBL	North British Locomotive Co., Glasgow
NW	Nasmyth Wilson, Manchester
O&K	Orenstein & Koppel, Berlin
RCF	Railway Coach Factory, Kapurthala
RS	Robert Stephenson, Newcastle-upon-Tyne, UK
SFAC	Societe des Forges et Ateliers, Creusot
SIG	Schweirische Industrie Gesselschaft
SLM	Schweizerische Lokomotiv- und Maschinenfabrik, Winterthur, Switz.
TELCO	Tata Engineering and Locomotive Co.
USATC	US Army Transportation Corps., USA
WB	William G. Bagnall, Stafford, UK
WIL	Wagon India Ltd. (an intermediary firm for wagon contracts)

 

Organizations & Corporations
AIRF	All-India Railwaymen's Federation (union organization)
BMRTC	Bangalore Metropolitan Rail Transit Corporation, Ltd.
BPT	Bombay Port Trust (later MPT)
CMC	Computer Maintenance Corporation, also Calcutta Metro Corporation
COFMOW	Central Organization for the Modernization of Workshops
CONCOR	Container Corporation of India
COOIS	Central Organization for Operations Information Systems
CORE	Central Organization for Railway Electrification
COS	Central Office of Standards (predecessor of RDSO)
CRIS	Centre for Railway Information Systems
CTC	Calcutta Tramways Corporation
DCW	Diesel Component Works, Patiala
DMRC	Delhi Metro Rail Corporation
ELRTS	Elevated Light Rail Transit System (proposed, Bangalore)
FNRM	Friends of the National Rail Museum
FROA	Federation of Officer's Associations (umbrella organization for railway officers' groups)
IPWE	Institution of Permanent Way Engineers
IRAS	Indian Railway Accounts Services (financial management)
IRC	Indian Railways Corporation (proposed)
IRCA	Indian Railway Conference Association (body that issues inspection guidelines, allots wagon codes, inspects workshops)
IRCON	Indian Railways Construction Company, now IRCON International Ltd., which takes on contract work to build railways in other countries (Iraq, Nepal, Indonesia...).
IRCOT	Indian Railways Central Organization for Telecom
IRCTC	Indian Railways Catering and Tourism Corporation
IREB	Indian Railways Executive Board (proposed)
IRFC	Indian Railways Finance Corporation
IRIATT	Indian Railways Institute of Advanced Track Technology
IRICEN	Indian Railways Institute of Civil Engineering, Pune
IRIEEN	Indian Railways Institute of Electrical Engineering, Nasik
IRIMEE	Indian Railways Institute of Mechanical and Electrical Engineering, Jamalpur
IRISET	Indian Railways Insitute of Signal Engineering and Telecommunications, Secunderabad
IRMS	Indian Railway Medical Services
IRPHA	Indian Railway Public Health Association
IRPS	indian Railway Personnel Services (human resources)
IRRA	Indian Railways Regulatory Authority (proposed)
IRSE	Indian Railway Service of Engineers
IRSEE	Indian Railway Service of Electrical Engineers
IRSME	Indian Railway Service of Mechanical Engineers
IRSS	Indian Railway Stores Services (inventory control)
IRSSE	Indian Railway Service of Signal Engineers
IRSTE	Indian Railway Signal and Telecom Engineering
IRTS	Indian Railway Traffic Services (management, marketing)
ISRS	Indian Steam Railway Society
ITB	International Tourist Bureau (New Delhi)
KRCL	Konkan Railway Corporation, Ltd.
KRDC	Konkan Railway Development Corporation
K-RIDE	Rail Infrastructure Development Corporation (Karnataka) Ltd.
KRIST	Konkan Railway Institute for Staff Training
KMRT	Kolkata Mass Rapid Transit
LRDSS	Long Range Decision Support System
LRTS	Light Rail Transit System (proposed, Kolkata)
MPT	Mumbai Port Trust (see BPT)
MRSP	Model Railway Society of Pune
MRTS	Mass Rapid Transit System (Chennai)
MRVC	Mumbai Rail Vikas Corporation
MTP	Metropolitan Transport Project (Railways), Bombay
MUTP	Mumbai Urban Transport Project (a World Bank project)
NFIR	National Federation of Indian Railwaymen (union organization)
NRM	National Rail Museum, New Delhi
PRCL	Pipavav Railway Corporation Ltd.
NRMU	National Railway Mazdoor Union (railway employees' trade union)
RB	Railway Board
RBSS	Railway Board Secretariat Services (part of Railway Ministry)
RCIL	Railtel Corporation of India, Ltd.
RDSO	Research, Design and Standards Organization
ROMA	Railway Officers' Medical Association
RPF	Railway Protection Force (also see below, Miscellaneous)
RSC	Railway Staff College, Vadodara
RITES	Rail India Technical and Economic Services, which takes on planning, design, and operational work in other countries (Angola, Mozambique, Zimbabwe, Botswana, Mexico, Zambia, Nepal, etc.).
RTRC	Railway Testing and Research Centre (a predecessor of RDSO)
RWWCO	Railway Women's Welfare Central Organization
RVNL	Rail Vikas Nigam Ltd.
SGE	Siemens and General Electric Railway Signal Co., Ltd.
WAP	Wheel and Axle Plant, Yelahanka (also a loco classification :-) )

 

Trains
AP	Andhra Pradesh Express
DQ	The Deccan Queen
GT	Grand Trunk Express
JJ	Jayanti Janata Express
KK	Karnataka-Kerala Express
TN	Tamil Nadu Express
POW	Palace on Wheels

 

Railways (former and current)
ADCR	Agra-Delhi Chord Railway
BAR	Bengal Assam Railway (in 1947, renamed East Bengal Rly., and in 1961, renamed Pakistan Eastern Rly.)
BB&CI / BB&CIR (BBCIR)	Bombay, Baroda, and Central India Railway
BCR	Bengal Central Railway
BDR	Bengal Dooars Railway, also Bankura Damodar Railway
BESR	Bilaspur - Etawah State Railway
BLR	Barsi Light Railway
BMR	Burma Mines Railway
BNR	Bengal Nagpur Railway
BNWR	Bengal North-Western Railway
BPR	Bengal Provincial Railway
BR	Burma Railway
BRC	Burma Railways Corporation
CBR	Cooch Behar Railway
CGR	Ceylon Government Railway
CR	Central Railway
CSER	Calcutta and South-Eastern Railway
DHR	Darjeeling Himalayan Railway
DMSR	Dhond-Manmad State Railway (Dhond = Daund)
DRLR	Dehri Rohtas Light Railway
DSR	Drangdhara State Railway
EBR	East Bengal State Railway
ECR	East Coast Railway
EIR	East Indian Railway
EPR	Eastern Punjab Railway
ER	Eastern Railway
GBSR	Gaekwar's Baroda State Railway
GIPR	Great Indian Peninsular Railway
GLR	Gwalior Light Railway (later Scindia State Railway)
GSR	Gondal State Railway
GSIR	Great Southern of India Railway
IGR	Indian Government Railways
IMR	Indian Midland Railway
IR	Indian Railways
ISR	Indian State Railway
IVSR	Indus Valley State Railway
JDR	Jamnagar and Dwarka Railway
JR	Jodhpur Railway
JSR	Jaipur State Railway
KHR	Khanai-Hindubagh Railway
KKTR	Kushalgarh-Kohat-Thal Railway
KR	Konkan Railway
KSR	Kalka Simla Railway
KVR	Kangra Valley Railway
LJR	Larkana-Jacobabad Railway
MLR	Matheran Light Railway
MR	Madras Railway
MSMR	Madras and Southern Mahratta Railway
MSR	Mysore State Railway
NER	North-eastern Railway
NEFR, NFR	North-East Frontier Railway
NMR	Nilgiri Mountain Railway
NR	Northern Railway
NGSR	Nizam's Guaranteed State Railway
NSR	Nizam's State Railway
NWR	North Western Railway (in 1961, renamed Pakistan Western Rly.)
O&RR, ORR	Oudh and Rohilkhund Railway
OTR	Oudh and Tirhut Railway
PDB	Piplod Devgad Baria Railway
PLR	Parlakimedi Light Railway
PNSR	Punjab Northern State Railway
PR	Pakistan Railways
PSMT	Patiala State Monorail Trainways
RDR	Raipur Dhamtari Railway
RKR	Rohilkhund Kumaon Railway
RMR	Rajputana Malwa Railway
SCR	South-central Railway
SER	South-eastern Railway
SLR	Sri Lanka Railways
SIR	South Indian Railway
SMR	Southern Mahratta Railway
SPDR	Scinde, Punjab, and Delhi Railway
SR	Southern Railway
SSLR	Shahdara Saharanpur Light Railway
SSR	Scindia State Railway, also Sangli State Railway
TBLR	Tezpore-Balipara Light Railway
WCSR	Wardha Coal State Railway
WIPR	West of India Portuguese Railway
WR	Western Railway

 

Technical acronyms (loosely defined — see the miscellaneous section also.)
ABS	Automatic Block Signalling
ACD	Anti-Collision Device
ADAM	ARTS Data Manager (system for managing EPROMs and station configuration cartridges for ARTS)
AE	Automatic Emergency or Auto-Emergency (type of brake system)
AFTC	Audio Frequency Track Circuiting
ATC	Automated Train Control
ATP	Automatic Train Protection
ATS	Automatic Train Stop
AVB	Automatic Vacuum Brake
ATS	Automatic Train Stop
BPC	Brake Power Certificate (issued before train departure)
BS	Braking in Series configuration
BSL	Block Section Limit
BSP	Braking in Series-Parallel configuration
CDO	Coaching Depot
CLS	Colour-light signalling
COCR	Confirmatory Oscillograph Car Run
COFC	Container on flat car
CTC	Centralised Traffic Control
CTR	Complete Track Renewal
CWR	Continuous Welded Rail (0.5km and longer sections of welded rail)
DAC	Digital Axle Counter
DBFO	Design-Build-Finance-Operate (a scheme for private parties to build and run railway lines with IR's help)
DJ	From the French disjoncteur, the main circuit breaker of an electric loco (usually pneumatically operated, roof-mounted)
DLBI	Double Line Block Instrument
DEMU	Diesel-Electric Multiple Unit
DETC	Diesel-Electric Tower Car
DHMU	Diesel Hydraulic Multiple Unit (hydraulic transmission DMU)
DMH	Dead Man's Handle (on EMUs)
DMU	Diesel Multiple Unit
DPC	Driving Power Car
DS	Disconnecting Switch (to switch off OHE power to loco circuits, usually manual)
DSC	Dual-Stacked Container service (or Double-Stacked Container)
DTC	Driving Trailer Car (unpowered driving car in EMU rake)
DW	Double wire (of semaphore signals)
EA	Extra (time) Allowed (make-up time noted in working time-tables)
ELCM	Electronic Load Control Module (governor for DEMUs and other diesels).
EMU	Electric Multiple Unit
EOG	End-On Generator Car
ETCS	European Train Control System
EY	Empty (notation for empty rake in real-time train information systems)
FEDL	Fully Electrified Double Line
FM	Fouling Mark
FMVFT	Frequency-modulated Voice-frequency Telegraph (used for control communications by signals / electric traction / traffic control staff)
FOR	Forward motion (position of master controller in loco)
FP	Fouling Point; also Feed Pipe (at couplings of vehicles)
GTO	Gate Turn-Off thyristor
HEP	Head-end Power (power from the loco for the coaches)
HFTC	High-Frequency Track Circuit
HOBC	High-Output Ballast Cleaner
HOG	Head-On Generator
HHPDMU	High-Horsepower Diesel Electric Multiple Unit
HPDMU	High-powered Diesel Multiple Unit
HSCB	High-speed Circuit Breaker
HT	High Tension
HTCBC	High Tensile-strength Centre-Buffer Coupler
HTS	High Tensile-strength Steel
IGBT	Insulated Gate Bipolar Transistor
JRI	Junction Route Indicator
LOB	Lube Oil Balance
LTPDS	Live Train Position Display System
LVC	Last Vehicle Check (automated detection of rake integrity)
LWR	Long Welded Rail (5-15 rails welded together in a section)
MACL, MACLS	Multiple-Aspect Colour-Light signalling
MCB	Master Circuit Breaker (in locos)
MCI	Malleable Cast Iron
MEMU	Main-line Electric Multiple Unit
MLRI	Multi-Lamp Route Indicator
MNI	Modified Non-Interlocked (in working timetables)
MOG	Mid-On Generator Car
MOT	Motoring (position of master controller in loco)
NBT	Neale's Ball Token
NI	Non-Interlocked (in working timetables)
NTES	National Train Enquiry System
NX	eNtrance-eXit (interlocking panels)
OCV	Other Coaching Vehicle - non-passenger coaches, e.g., pantry cars.
OFC	Optical Fibre Cable
OHE	Overhead Equipment (or foreman for same)
OMS	Oscillation Monitoring System
PCS	Pneumatic Control System (loco shut-off/idling control which takes effect on application of emergency brakes)
PCV	Passenger Carrying Vehicle (regular passenger coaches, as distinct from OCV - restaurant cars, mail cars, etc.)
PI	Panel Interlocking
POET	Passenger Operated Enquiry Terminal
RCC	Remote Control Centre (for electric traction) Also, Reinforced Cement Concrete (Also see below in Miscellaneous)
REV	Reverse motion (position of master controller in loco), Reverser
ROSHAN	Rolling Stock Health Analyst (accelerometers and other equipment that monitor coach movement and report deviations from normal behaviour).
RPC	Resistance Power Control (or Compartment) (in EMU power cars)
SCADA	Supervisory Control and Data Acquisition (monitoring and control system for remote control of electric traction systems)
SE	Superelevation (of curved track)
S/L	Shunting Limit
SLBI	Single Line Block Instrument
SOD	Schedule of Dimensions
SPAD	Signal Passed At Danger
SPTM	Self-Printing Ticket Machine
SSDAC	Solid State Digital Axle Counter
SSI	Solid State Interlocking
STR	Schedule of Technical Requirements
STRI	Stencil type Route Indicator
SW	Single wire (of semaphore signals)
SWR	Short Welded Rail (2-4 rails welded together in a section) Also: Station Working Rules
TAB	Train Air Brake
TALQ	Two-Aspect Lower Quadrant
TAWD	Train Actuated Warning Device
TBTR	Through Bridge Timber Renewal
TFR	Through Fitting Renewal
TLC	Traction Locomotive Controller
TM	Traction Motor
TMS	Train Management System (train monitoring used in Bombay suburban sections)
TOFC	Trailer on flat car
T/out	Turnout
TPC	Traction Power Controller
TRC	Track Recording Car
TRO	Traction Rolling-stock Operations
TRR	Through Rail Renewal
TRT	Traffic Recovery Time (a kind of make-up time allotment in working timetable)
TSS	Traction Sub-Station
TSR	Through Sleeper Renewal
TTR	Through Turnout Renewal
TWR	Through Weld Renewal
UPF	Unity Power Factor
USFD	Ultrasonic Flaw Detection
VCC	Vacuum Continuity Certificate (issued before train departure)
VCB	Vacuum Circuit Breaker
VRP	Voltage Regulating Panel
WF	Weak Field
WILD	Wheel Impact Load Detector
WSR	Wheel Slip Relay

Source - IFRCA.org