legacy code · unmeasured
a system whose parameter window no living maintainer has measured, still inside it, maintained without knowing where its walls are.
Examples
- The Therac-25 radiation therapy machine malfunctioned in 1985 due to unmeasured race conditions in code originally written in the 1970s. computing
- The New York City subway's signal system, largely unchanged since the 1940s, runs trains with timetables adjusted by hand-drawn chalk logs. engineering
- Farmers in the Sahel maintain irrigation ditches laid during French colonial rule, though no one recalls the original grading specifications. institutions
Emergence
from: window wall parameter maintenance drift model self-model inside know live measure measurement still system
through: The interaction of maintenance, unmeasured boundaries, and the absence of a cognitive model of those boundaries allows the persistence of a system in ignorance of its own limits.
- unmeasured persistence
- maintained ignorance
- precarious stability
Chain to foundations
- legacy codeL15
- windowL7
- parameterL4
- rangeL3
- boundaryL2 (shown above)
- persistL1 (shown above)
- changeL1 (shown above)
- outsideL6
- partL1 (shown above)
- wallL10
- parameterL4 (shown above)
- maintenanceL14
- workL3
- parameterL4 (shown above)
- windowL7 (shown above)
- holdL13
- touchL3
- forceL12
- keepL5
- motionL2 (shown above)
- insideL5 (shown above)
- driftL11
- parameterL4 (shown above)
- changeL1 (shown above)
- goL3
- makeL4 (shown above)
- nothingL10
- noneL9
- differenceL1 (shown above)
- amountL8
- sizeL2
- quantityL7
- numberL6
- differenceL1 (shown above)
- distinctL3
- differenceL1 (shown above)
- othersL2 (shown above)
- othersL2 (shown above)
- spaceL0 (shown above)
- marksL5
- differenceL1 (shown above)
- partL1 (shown above)
- changeL1 (shown above)
- patternL0 (shown above)
- surfaceL4 (shown above)
- sizeL2 (shown above)
- numberL6
- numberL6 (shown above)
- offL2
- spaceL0 (shown above)
- differenceL1 (shown above)
- noneL9
- wayL9
- modelL9
- self-modelL14
- insideL5 (shown above)
- knowL7
- informationL6 (shown above)
- stateL2 (shown above)
- liveL2
- measureL13
- measurementL12
- regularityL10
- quantityL7 (shown above)
- spaceL0 (shown above)
- sizeL2 (shown above)
- applicationL10
- useL6
- purposeL9
- goalL6
- stateL2 (shown above)
- differenceL1 (shown above)
- needL5
- stateL2 (shown above)
- differenceL1 (shown above)
- persistL1 (shown above)
- conditionL3 (shown above)
- objectL4 (shown above)
- workL3 (shown above)
- meaningL8
- informationL6 (shown above)
- differenceL1 (shown above)
- stateL2 (shown above)
- knowledgeL7
- informationL6 (shown above)
- peopleL6
- othersL2 (shown above)
- setsL3 (shown above)
- persistL1 (shown above)
- distinctL3 (shown above)
- entitiesL4 (shown above)
- interactingL4
- interactionL2 (shown above)
- touchL3 (shown above)
- groupsL5
- timeL0 (shown above)
- patternL0 (shown above)
- goalL6
- processL4 (shown above)
- specificL3
- justL2
- differenceL1 (shown above)
- patternL0 (shown above)
- differenceL1 (shown above)
- othersL2 (shown above)
- justL2
- differenceL1 (shown above)
- processL4 (shown above)
- propertyL3
- stateL2 (shown above)
- differenceL1 (shown above)
- applyingL8
- patternL0 (shown above)
- recordedL11
- registerL10
- saveL6
- informationL6 (shown above)
- recordsL11
- regularL1
- useL6 (shown above)
- stillL3
- systemL5
- setsL3 (shown above)
- partL1 (shown above)
- structureL2 (shown above)
- interactionL2 (shown above)
- windowL7
Neighborhood
Concepts that depend on this one above; what it is built from below.