| Section 821-01: General concepts and terms |
| 821-01-01 | railway signalling | |
| 821-01-02 | security apparatus, <for railways> | |
| 821-01-03 | signalling system, <for railways> | |
| 821-01-04 | lineside signalling | |
| 821-01-05 | automatic signalling | |
| 821-01-06 | continuous signalling | |
| 821-01-07 | intermittent signalling | |
| 821-01-08 | route signalling | |
| 821-01-09 | speed signalling | |
| 821-01-10 | fail-safe, adj | |
| 821-01-11 | safety installation | |
| 821-01-12 | section regulator | |
| 821-01-13 | regulation | |
| 821-01-14 | signal regulations | |
| 821-01-15 | main running line | |
| 821-01-16 | siding | |
| 821-01-17 | operation, <of points, of a device> | |
| 821-01-18 | ground frame operation | |
| 821-01-19 | permission | |
| 821-01-20 | authority for shunting | |
| 821-01-21 | overlap, <in signalling> | |
| 821-01-22 | route, <in signalling> | |
| 821-01-23 | fouling point | |
| 821-01-24 | reversible working | |
| 821-01-25 | temporary single-line working | |
| 821-01-26 | flank protection | |
| 821-01-27 | line subject to speed restriction | |
| 821-01-28 | control, <in signalling> | |
| 821-01-29 | central control of traffic | |
| 821-01-30 | direct control, <in signalling> | |
| 821-01-31 | remote control, <in signalling> | |
| 821-01-32 | local control, <in signalling> | |
| 821-01-33 | normal position | |
| 821-01-34 | reverse position | |
| 821-01-35 | resetting device | |
| 821-01-36 | prohibition device | |
| 821-01-37 | clearing of a track | |
| 821-01-38 | effect of train | |
| 821-01-39 | rigid transmission | |
| 821-01-40 | wire transmission | |
| 821-01-41 | broken-wire detector | |
| 821-01-42 | checking circuit | |
| 821-01-43 | checking equipment | |
| 821-01-44 | checking of an apparatus | |
| 821-01-45 | correspondence checking | |
| 821-01-46 | positional checking | |
| 821-01-47 | repeater, <in signalling> | |
| 821-01-48 | electromechanical repeater | |
| 821-01-49 | light repeater | |
| 821-01-50 | command, <in signalling> | |
| 821-01-51 | commercial speed | |
| 821-01-52 | degraded modes, pl | |
| 821-01-53 | environmental conditions, <for signalling equipment> pl | |
| 821-01-54 | equipment housing | |
| 821-01-55 | exclusive guideway | |
| 821-01-56 | generic application | |
| 821-01-57 | generic product | |
| 821-01-58 | grade of automation | |
| 821-01-59 | guideway clearance | |
| 821-01-60 | interchangeability, <of system components> | |
| 821-01-61 | interoperability of a transport network | |
| 821-01-62 | mission of a train | |
| 821-01-63 | movement authority | |
| 821-01-64 | operations control centre | |
| 821-01-65 | operations control HMI | |
| 821-01-66 | operations staff | |
| 821-01-67 | passenger transfer area | |
| 821-01-68 | passenger transfer door | |
| 821-01-69 | platform track | |
| 821-01-70 | platform waiting area | |
| 821-01-71 | safe places, pl | |
| 821-01-72 | safety space | |
| 821-01-73 | safety-related, adj | |
| 821-01-74 | specific application | |
| 821-01-75 | supervise, verb | |
| 821-01-76 | transfer area | |
| 821-01-77 | transport authority | |
| 821-01-78 | zero speed status | |
| 821-01-79 | zone of protection | |
| Section 821-02: Signals |
| 821-02-01 | signal, <in railway signalling> | |
| 821-02-02 | aspect of a signal | |
| 821-02-03 | indication of a signal | |
| 821-02-04 | classification of signal aspects | |
| 821-02-05 | signal on | |
| 821-02-06 | open position, <of a signal> | |
| 821-02-07 | signal at danger | |
| 821-02-08 | clear signal | |
| 821-02-09 | out-of-commission signal | |
| 821-02-10 | masked signal | |
| 821-02-11 | signal out | |
| 821-02-12 | caution aspect | |
| 821-02-13 | manual signalling | |
| 821-02-14 | manually-operated signal | |
| 821-02-15 | mechanical signalling | |
| 821-02-16 | mechanical signal | |
| 821-02-17 | semaphore signal | |
| 821-02-18 | semaphore arm | |
| 821-02-19 | violet square signal | |
| 821-02-20 | disc signal | |
| 821-02-21 | signal circuit controller | |
| 821-02-22 | coupled signals, pl | |
| 821-02-23 | signal bracket | |
| 821-02-24 | bracketed signal | |
| 821-02-25 | signal gantry | |
| 821-02-26 | bell-code signalling | |
| 821-02-27 | detonator | |
| 821-02-28 | detonator placer | |
| 821-02-29 | electric signalling | |
| 821-02-30 | automatic signal | |
| 821-02-31 | semi-automatic signal | |
| 821-02-32 | automatic signal replacement | |
| 821-02-33 | light signalling | |
| 821-02-34 | light signal, <for signalling> | |
| 821-02-35 | multiple-aspect light signal | |
| 821-02-36 | position light signal | |
| 821-02-37 | marker light | |
| 821-02-38 | light unit | |
| 821-02-39 | single light unit | |
| 821-02-40 | multi-unit light signal | |
| 821-02-41 | signal light, <for signalling> | |
| 821-02-42 | flashing light signal | |
| 821-02-43 | phantom light | |
| 821-02-44 | searchlight signal | |
| 821-02-45 | hot strip | |
| 821-02-46 | side light | |
| 821-02-47 | signal lamp | |
| 821-02-48 | back light, <of a signal> | |
| 821-02-49 | approach lighting | |
| 821-02-50 | positioning of signals | |
| 821-02-51 | warning presignalling distance | |
| 821-02-52 | sighting distance | |
| 821-02-53 | distance between signals | |
| 821-02-54 | signal headway | |
| 821-02-55 | signal in rear | |
| 821-02-56 | signal identification plate | |
| 821-02-57 | signal type plate | |
| 821-02-58 | signal background | |
| 821-02-59 | signal hood | |
| 821-02-60 | signal not in use sign | |
| 821-02-61 | warning board | |
| 821-02-62 | execution signal | |
| 821-02-63 | warning signal, <for train driver> | |
| 821-02-64 | speed restriction warning signal | |
| 821-02-65 | speed restriction execution signal | |
| 821-02-66 | speed warning board | |
| 821-02-67 | speed limit execution board | |
| 821-02-68 | speed limit termination indicator | |
| 821-02-69 | line speed indicator | |
| 821-02-70 | route indicator | |
| 821-02-71 | distant route indicator | |
| 821-02-72 | direction indicating board | |
| 821-02-73 | fouling point indicator | |
| 821-02-74 | tail lamp | |
| 821-02-75 | reflectorized board | |
| 821-02-76 | stop-board | |
| 821-02-77 | vehicle on-line indicator | |
| 821-02-78 | whistle board | |
| 821-02-79 | stop signal, <for signalling> | |
| 821-02-80 | main signal | |
| 821-02-81 | entry signal | |
| 821-02-82 | exit signal | |
| 821-02-83 | departure signal | |
| 821-02-84 | departure light signal | |
| 821-02-85 | common signal | |
| 821-02-86 | main signal with shunting aspect | |
| 821-02-87 | special purpose subsidiary signal | |
| 821-02-88 | subsidiary signal | |
| 821-02-89 | supplementary signal indication | |
| 821-02-90 | block signal, <for signalling> | |
| 821-02-91 | permissive signal, <in a block system> | |
| 821-02-92 | stop and proceed signal | |
| 821-02-93 | call-on signal | |
| 821-02-94 | permissive light | |
| 821-02-95 | shunt signal | |
| 821-02-96 | shot shunting signal | |
| 821-02-97 | ground signal | |
| 821-02-98 | limit of shunt indicator | |
| 821-02-99 | humping signal | |
| 821-02-100 | distant signal | |
| 821-02-101 | outer distant signal | |
| 821-02-102 | pre-distant signal | |
| 821-02-103 | repeating signal | |
| 821-02-104 | short route signal | |
| 821-02-105 | speed regulating signal | |
| 821-02-106 | signal for work-site | |
| 821-02-107 | intermittent warning signal | |
| 821-02-108 | junction signal | |
| 821-02-109 | hand signal | |
| 821-02-110 | points indication signal | |
| 821-02-111 | brake test signal | |
| 821-02-112 | protection signal | |
| 821-02-113 | special protection signal | |
| 821-02-114 | wrong road signal | |
| 821-02-115 | driver's indication signal | |
| 821-02-116 | end of catenary signal | |
| 821-02-117 | lower pantograph advance warning sign | |
| 821-02-118 | lower pantograph execution sign | |
| 821-02-119 | lower pantograph cancellation sign | |
| 821-02-120 | switch-off-power warning sign | |
| 821-02-121 | switch-off-power execution signal | |
| 821-02-122 | switch-on-power indicator board | |
| 821-02-123 | signal fault | |
| 821-02-124 | whistle | |
| 821-02-125 | St. Andrew's cross | |
| 821-02-126 | warning signal, <for staff on the track> | |
| 821-02-127 | driving on sight | |
| Section 821-03: Train detection |
| 821-03-01 | track circuit | |
| 821-03-02 | centre-fed track circuit | |
| 821-03-03 | double-rail track circuit | |
| 821-03-04 | single-rail track circuit | |
| 821-03-05 | jointless track circuit | |
| 821-03-06 | superimposible track circuit | |
| 821-03-07 | direct current track circuit | |
| 821-03-08 | alternating current track circuit | |
| 821-03-09 | capacitor fed alternating current track circuit | |
| 821-03-10 | inductance fed alternating current track circuit | |
| 821-03-11 | coded current track circuit | |
| 821-03-12 | high-voltage pulsed track circuit | |
| 821-03-13 | track relay | |
| 821-03-14 | insulated rail | |
| 821-03-15 | insulated section of track | |
| 821-03-16 | insulated joint | |
| 821-03-17 | insulating ferrule | |
| 821-03-18 | insulating fishplate | |
| 821-03-19 | end post | |
| 821-03-20 | insulating side-plate | |
| 821-03-21 | electric separation joint | |
| 821-03-22 | rail joint bond | |
| 821-03-23 | impedance bond | |
| 821-03-24 | resonant impedance bond | |
| 821-03-25 | track circuit compensating capacitors | |
| 821-03-26 | cut section of track circuit | |
| 821-03-27 | track circuit interrupter | |
| 821-03-28 | train shunt | |
| 821-03-29 | loss of shunt | |
| 821-03-30 | drop shunt of a track | |
| 821-03-31 | prevent shunt | |
| 821-03-32 | shunt resistance | |
| 821-03-33 | ballast resistance | |
| 821-03-34 | treadle | |
| 821-03-35 | magnetic treadle | |
| 821-03-36 | electromechanical treadle | |
| 821-03-37 | delayed action electromechanical treadle | |
| 821-03-38 | electronic treadle | |
| 821-03-39 | directional treadle | |
| 821-03-40 | loop detection equipment | |
| 821-03-41 | axle counter | |
| 821-03-42 | counting point | |
| 821-03-43 | end-of-train detector | |
| 821-03-44 | line clear detection | |
| 821-03-45 | track occupancy indicator | |
| 821-03-46 | certificate of acceptance | |
| 821-03-47 | compatibility case | |
| 821-03-48 | factor of safety | |
| 821-03-49 | gabarit | |
| 821-03-50 | spot transmission | |
| 821-03-51 | train detection | |
| 821-03-52 | train integrity | |
| 821-03-53 | wheel detector | |
| Section 821-04: Operation and detection of points and other rail-mounted equipment |
| 821-04-01 | blade | |
| 821-04-02 | points, pl | |
| 821-04-03 | facing points | |
| 821-04-04 | trailing points | |
| 821-04-05 | arrival points | |
| 821-04-06 | shunting points | |
| 821-04-07 | trailable points | |
| 821-04-08 | non-resetting trailable points | |
| 821-04-09 | resetting trailable points | |
| 821-04-10 | intermediate points position | |
| 821-04-11 | trap points | |
| 821-04-12 | selective protective points | |
| 821-04-13 | catch points | |
| 821-04-14 | derailling points | |
| 821-04-15 | derailer | |
| 821-04-16 | point lock | |
| 821-04-17 | independent point lock | |
| 821-04-18 | dependent point lock | |
| 821-04-19 | slide-chair point lock and detector | |
| 821-04-20 | clamp lock | |
| 821-04-21 | securing bolt | |
| 821-04-22 | point machine | |
| 821-04-23 | point detector | |
| 821-04-24 | electric point detector | |
| Section 821-05: Interlocking and signal box equipment |
| 821-05-01 | signal box | |
| 821-05-02 | interlocking, <in railway signalling> | |
| 821-05-03 | central signal box | |
| 821-05-04 | centralized traffic control | |
| 821-05-05 | satellite interlocking | |
| 821-05-06 | track circuit diagram | |
| 821-05-07 | control panel | |
| 821-05-08 | indication panel | |
| 821-05-09 | locking table | |
| 821-05-10 | entrance-exit control | |
| 821-05-11 | geographical control panel | |
| 821-05-12 | individual switch operation | |
| 821-05-13 | individual points control | |
| 821-05-14 | group button | |
| 821-05-15 | signalman | |
| 821-05-16 | traffic controller | |
| 821-05-17 | main route | |
| 821-05-18 | shunt route | |
| 821-05-19 | route setting system | |
| 821-05-20 | route section | |
| 821-05-21 | composite route | |
| 821-05-22 | partial route | |
| 821-05-23 | conflicting routes, pl | |
| 821-05-24 | emergency route | |
| 821-05-25 | route locking | |
| 821-05-26 | complete route locking | |
| 821-05-27 | sectional route releasing | |
| 821-05-28 | manual cancellation of route | |
| 821-05-29 | automatic route release | |
| 821-05-30 | automatic working of a route | |
| 821-05-31 | route-programme machine | |
| 821-05-32 | cancellation device | |
| 821-05-33 | emergency release | |
| 821-05-34 | emergency replacement switch | |
| 821-05-35 | approach locking | |
| 821-05-36 | approach locking section | |
| 821-05-37 | approach control | |
| 821-05-38 | approach section | |
| 821-05-39 | directional control | |
| 821-05-40 | non-presetting control | |
| 821-05-41 | presetting control | |
| 821-05-42 | point release button | |
| 821-05-43 | opposing locking | |
| 821-05-44 | sequential locking | |
| 821-05-45 | rotation locking | |
| 821-05-46 | continuity locking | |
| 821-05-47 | all relay interlocking | |
| 821-05-48 | computer controlled relay interlocking | |
| 821-05-49 | geographical circuit interlocking | |
| 821-05-50 | free wiring | |
| 821-05-51 | electric lock | |
| 821-05-52 | combined electric lock and circuit controller | |
| 821-05-53 | safety relay | |
| 821-05-54 | break contact | |
| 821-05-55 | make contact | |
| 821-05-56 | change-over contact | |
| 821-05-57 | reverse contact | |
| 821-05-58 | normal contact | |
| 821-05-59 | single-element relay | |
| 821-05-60 | two-element relay | |
| 821-05-61 | bistable relay | |
| 821-05-62 | three-position relay | |
| 821-05-63 | relay set | |
| 821-05-64 | repeater relay | |
| 821-05-65 | signal proving | |
| 821-05-66 | signal lamp proving | |
| 821-05-67 | signal light proving | |
| 821-05-68 | key lock | |
| 821-05-69 | key transmitter | |
| 821-05-70 | speed discriminator | |
| 821-05-71 | time release | |
| 821-05-72 | absolute detection | |
| 821-05-73 | continuous detection | |
| 821-05-74 | transient detection | |
| 821-05-75 | solid state interlocking | |
| 821-05-76 | redundancy, <in a system> | |
| 821-05-77 | redundancy management | |
| 821-05-78 | self testing | |
| 821-05-79 | divergence, <in a redundant sytem> | |
| 821-05-80 | right-side failure | |
| 821-05-81 | wrong-side failure | |
| 821-05-82 | availability, <of a product> | |
| 821-05-83 | repairable modular redundancy | |
| 821-05-84 | processor interlocking | |
| 821-05-85 | panel multiplexer | |
| 821-05-86 | technician's terminal | |
| 821-05-87 | data preparation | |
| 821-05-88 | safe data transmission | |
| 821-05-89 | data link, <in railway signalling> | |
| 821-05-90 | data link module, <in railway signalling> | |
| 821-05-91 | signal module | |
| 821-05-92 | points module | |
| 821-05-93 | train detection module | |
| 821-05-94 | integrated electronic control centre | |
| 821-05-95 | signalman's control and display system | |
| 821-05-96 | automatic route setting equipment | |
| 821-05-97 | timetable processor | |
| 821-05-98 | train describer | |
| 821-05-99 | identification entry | |
| 821-05-100 | progression system | |
| Section 821-06: Block signalling system |
| 821-06-01 | block system | |
| 821-06-02 | block section | |
| 821-06-03 | absolute block | |
| 821-06-04 | permissive block | |
| 821-06-05 | absolute permissive block | |
| 821-06-06 | automatic block | |
| 821-06-07 | partly permissive automatic block | |
| 821-06-08 | manual block | |
| 821-06-09 | interlocking block | |
| 821-06-10 | telephone block | |
| 821-06-11 | fixed block | |
| 821-06-12 | moving block | |
| Section 821-07: Level crossing protection |
| 821-07-01 | level crossing | |
| 821-07-02 | road warning device | |
| 821-07-03 | road barrier | |
| 821-07-04 | full barrier | |
| 821-07-05 | half-barrier | |
| 821-07-06 | half-barrier level crossing | |
| 821-07-07 | double half-barrier level crossing | |
| 821-07-08 | manually controlled level crossing | |
| 821-07-09 | automatic level crossing | |
| 821-07-10 | indication of an automatic level crossing | |
| 821-07-11 | cycle duration | |
| 821-07-12 | striking-in distance | |
| 821-07-13 | barrier machine | |
| 821-07-14 | automatic danger zone detector | |
| Section 821-08: Automatic train protection |
| 821-08-01 | automatic train protection system | |
| 821-08-02 | automatic train control system | |
| 821-08-03 | train speed supervision | |
| 821-08-04 | cab signalling | |
| 821-08-05 | acknowledge button | |
| 821-08-06 | vigilance device | |
| 821-08-07 | automatic warning system | |
| 821-08-08 | automatic train stop | |
| 821-08-09 | automatic train stop override | |
| 821-08-10 | train stop | |
| 821-08-11 | braking speed supervision | |
| 821-08-12 | partial supervision | |
| 821-08-13 | locomotive magnet | |
| 821-08-14 | track magnet | |
| 821-08-15 | beacon, <in signalling> | |
| 821-08-16 | transponder, <in signalling> | |
| 821-08-17 | active beacon | |
| 821-08-18 | track conductor system | |
| 821-08-19 | continuous automatic train protection transmission system | |
| 821-08-20 | intermittent automatic train protection transmission system | |
| 821-08-21 | release at red signal, <in an intermittent automatic train protection transmission system> | |
| 821-08-22 | track-to-train transmission | |
| 821-08-23 | advance warning cab signalling | |
| 821-08-24 | service braking distance | |
| 821-08-25 | emergency braking distance | |
| 821-08-26 | target distance | |
| 821-08-27 | target speed | |
| 821-08-28 | infill information point, <in an intermittent automatic train protection transmission system> | |
| Section 821-09: Automatic train operation |
| 821-09-01 | automatic train operation | |
| 821-09-02 | wheel revolution counter | |
| 821-09-03 | control location, <in an automatic train operation system> | |
| 821-09-04 | executive point, <in an automatic train operation system> | |
| 821-09-05 | train location, <in an automatic train operation system> | |
| 821-09-06 | zero point, <in an automatic train operation system> | |
| 821-09-07 | radio automatic train operation | |
| 821-09-08 | automated urban guided transport | |
| 821-09-09 | automatic mode | |
| 821-09-10 | driverless train operation | |
| 821-09-11 | non-automated train operation | |
| 821-09-12 | on-sight train operation | |
| 821-09-13 | semi-automated train operation | |
| 821-09-14 | unattended train operation | |
| Section 821-10: Miscellaneous |
| 821-10-01 | hot box detector | |
| 821-10-02 | fall detector | |
| 821-10-03 | bridge displacement detector | |
| 821-10-04 | land-slide detector | |
| Section 821-11: Communication in transmission systems |
| 821-11-01 | absolute time stamp | |
| 821-11-02 | access protection | |
| 821-11-03 | additional data, pl | |
| 821-11-04 | authentic message | |
| 821-11-05 | authenticity | |
| 821-11-06 | closed transmission system | |
| 821-11-07 | confidentiality | |
| 821-11-08 | corrupted message | |
| 821-11-09 | cryptographic technique | |
| 821-11-10 | cyclic redundancy check, <for communication in transmission systems> | |
| 821-11-11 | data, <for communication in transmission systems> pl | |
| 821-11-12 | implicit data, pl | |
| 821-11-13 | data corruption | |
| 821-11-14 | defence | |
| 821-11-15 | delayed message | |
| 821-11-16 | deleted message | |
| 821-11-17 | double time stamp | |
| 821-11-18 | error | |
| 821-11-19 | failure, <of an item> | |
| 821-11-20 | fault, <in a system> | |
| 821-11-21 | feedback message | |
| 821-11-22 | hacker | |
| 821-11-23 | hazard analysis | |
| 821-11-24 | information, <in a process> | |
| 821-11-25 | inserted message | |
| 821-11-26 | integrity, <of information> | |
| 821-11-27 | manipulation detection code | |
| 821-11-28 | masqueraded message | |
| 821-11-29 | message, <in transmission systems> | |
| 821-11-30 | message authentication code | |
| 821-11-31 | message enciphering | |
| 821-11-32 | message errors, pl | |
| 821-11-33 | message integrity | |
| 821-11-34 | message stream | |
| 821-11-35 | non-cryptographic safety code | |
| 821-11-36 | open transmission system | |
| 821-11-37 | port, <for signalling and telecommunications apparatus> | |
| 821-11-38 | random failure | |
| 821-11-39 | redundancy check | |
| 821-11-40 | redundant data, pl | |
| 821-11-41 | relative time stamp | |
| 821-11-42 | repeated message | |
| 821-11-43 | resequenced message | |
| 821-11-44 | safe fall-back state | |
| 821-11-45 | safety code | |
| 821-11-46 | safety integrity level | |
| 821-11-47 | safety reaction | |
| 821-11-48 | sequence number | |
| 821-11-49 | source and destination identifier | |
| 821-11-50 | systematic failure | |
| 821-11-51 | threat | |
| 821-11-52 | time stamp | |
| 821-11-53 | timeliness | |
| 821-11-54 | transmission code | |
| 821-11-55 | transmission system, <in communication, signalling and processing systems> | |
| 821-11-56 | unauthorized access | |
| 821-11-57 | user data, pl | |
| 821-11-58 | valid message | |
| 821-11-59 | validity | |
| Section 821-12: Reliabilty, availability, maintainability and safety |
| 821-12-01 | accepting body | |
| 821-12-02 | accident | |
| 821-12-03 | apportionment | |
| 821-12-04 | assessment | |
| 821-12-05 | assessor | |
| 821-12-06 | authorization | |
| 821-12-07 | causal analysis | |
| 821-12-08 | COTS software | |
| 821-12-09 | commissioning | |
| 821-12-10 | common cause failures, pl | |
| 821-12-11 | compliance, <in signalling> | |
| 821-12-12 | configuration | |
| 821-12-13 | configuration management | |
| 821-12-14 | consequence analysis | |
| 821-12-15 | cross-acceptance | |
| 821-12-16 | design | |
| 821-12-17 | design authority | |
| 821-12-18 | designer | |
| 821-12-19 | diversity | |
| 821-12-20 | failure mode | |
| 821-12-21 | failure rate | |
| 821-12-22 | fault detection time | |
| 821-12-23 | fault tolerance, <in signalling> | |
| 821-12-24 | firmware, <in signalling> | |
| 821-12-25 | function, <of a product> | |
| 821-12-26 | generic software | |
| 821-12-27 | hazard log | |
| 821-12-28 | human error | |
| 821-12-29 | implementation | |
| 821-12-30 | implementer | |
| 821-12-31 | functional independence | |
| 821-12-32 | human independence | |
| 821-12-33 | physical independence | |
| 821-12-34 | individual risk | |
| 821-12-35 | logistic support | |
| 821-12-36 | mission | |
| 821-12-37 | mission profile | |
| 821-12-38 | negation | |
| 821-12-39 | negation time | |
| 821-12-40 | product, <in signalling> | |
| 821-12-41 | programmable logic controller | |
| 821-12-42 | railway authority | |
| 821-12-43 | railway infrastructure authority | |
| 821-12-44 | railway support industry | |
| 821-12-45 | random failure integrity | |
| 821-12-46 | random fault | |
| 821-12-47 | RAM programme | |
| 821-12-48 | rolling stock operator | |
| 821-12-49 | safe state | |
| 821-12-50 | safety acceptance | |
| 821-12-51 | safety approval | |
| 821-12-52 | safety authority | |
| 821-12-53 | safety case | |
| 821-12-54 | safety integrity | |
| 821-12-55 | safety life cycle | |
| 821-12-56 | safety management | |
| 821-12-57 | safety plan | |
| 821-12-58 | safety process | |
| 821-12-59 | safety regulatory authority | |
| 821-12-60 | safety-related software | |
| 821-12-61 | software | |
| 821-12-62 | software maintainability | |
| 821-12-63 | software maintenance | |
| 821-12-64 | software safety integrity level | |
| 821-12-65 | stress profile | |
| 821-12-66 | system life cycle | |
| 821-12-67 | system safety integrity level | |
| 821-12-68 | systematic failure integrity | |
| 821-12-69 | systematic fault, <in signalling> | |
| 821-12-70 | technical safety report | |
| 821-12-71 | tolerable risk | |
| 821-12-72 | validation | |
| 821-12-73 | validator | |
| 821-12-74 | verification | |
| 821-12-75 | verifier | |