Guide cards · the canonical list
The core disciplines
46 disciplines across 5 drawers, every code ending in zero. This is the tier meant to be adopted whole: nothing in it depends on whose card box it is, and nothing in it is here because of one filer's interests. Cut a tab for each row and you have a working skeleton.
Read a code as drawer + discipline + sub-discipline — one digit, then two, then one. Two digits for the discipline leaves 99 slots per drawer, so a drawer you work in daily can keep sprouting for decades without a renumber.
Which is the whole reason this page can stay canonical. Every row here ends in zero, so every discipline carries nine unused units digits. Your own sub-disciplines go there — and a table you extend only in the fourth digit is a table whose codes never move. How to extend it →
The second column is the one that does the work. It answers does this card go here? rather than naming a field, and where two disciplines genuinely compete it says which one wins and sends you to the other. Not sure which row? →
1000 Humanities
- 1010 Philosophy Metaphysics, ethics, aesthetics, epistemology, and the philosophy of any X. Formal logic is 4010.
- 1020 Religion and theology Comparative religion, mythology, scripture, doctrine, ritual, and every specific tradition. One card per tradition, then branch beneath it.
- 1030 History Historiography, periods, regions, and historical biography. A discipline's own history files with that discipline, not here.
- 1040 Language and linguistics Phonetics, grammar, semantics, etymology, translation, and individual languages. The study of language; writing it well is 1060.
- 1050 Literature Poetry, prose, drama as text, criticism, genre, and national literatures. Reading it; writing it is 1060.
- 1060 Writing and rhetoric Composition, style, argument, storytelling, editing. Craft rather than criticism. Writing that sells something is 5060.
- 1070 Visual arts Painting, sculpture, photography, printmaking, craft, and art history.
- 1080 Performing arts Music, theatre, dance, and film, including the technical craft of performance.
2000 Social science
- 2010 Anthropology Cultural, physical, and linguistic anthropology; ethnography, folklore, kinship.
- 2020 Archaeology Material remains, excavation, dating methods, and specific sites and cultures.
- 2030 Sociology Social structure, class, demography, institutions, deviance, family, and social movements.
- 2040 Psychology Cognitive, clinical, developmental, and social psychology. Attention, habit, motivation, and memory file here; their neural machinery is 3050.
- 2050 Economics Micro, macro, trade, monetary theory, behavioural economics. Theory of the economy; running a business is 5060.
- 2060 Political science Government, political theory, international relations, elections, power. Delivering policy is 5110.
- 2070 Geography Human geography, cartography, regional studies, GIS, place and space. Rock and weather are 3040.
- 2080 Communication and media Journalism, broadcasting, mass communication, platforms, media theory. Selling through them is 5060.
- 2090 Area and ethnic studies Work scoped to a region or an identity rather than to a method. Use when the region is the subject, not the setting.
- 2100 Futures and foresight Futurology, scenario planning, forecasting, long-range risk.
3000 Natural science
- 3010 Physics Mechanics, thermodynamics, electromagnetism, optics, quantum, relativity, particle physics.
- 3020 Chemistry Organic, inorganic, analytical, and physical chemistry; matter at the molecular level.
- 3030 Astronomy and space science Cosmology, astrophysics, planetary science, observation, and the science of spaceflight.
- 3040 Earth science Geology, meteorology, oceanography, hydrology, palaeontology, and climate as a physical system.
- 3050 Biology Genetics, cell and molecular biology, evolution, microbiology, botany, zoology, physiology, metabolism, neuroscience as mechanism.
- 3060 Ecology and environment Ecosystems, biodiversity, population dynamics, climate impact. How nature works; managing it is 5090.
4000 Formal science
- 4010 Logic Formal, mathematical, and philosophical logic; proof, validity, fallacy. Arguing persuasively is 1060.
- 4020 Mathematics Algebra, geometry, analysis, number theory, topology, discrete mathematics.
- 4030 Statistics and probability Distributions, inference, experimental design, sampling, and data analysis.
- 4040 Computer science Algorithms, data structures, computability, complexity, programming language theory. Theory; building software is 4050.
- 4050 Software engineering Design, architecture, testing, delivery, tooling, and team practice. The craft of shipping working systems.
- 4060 Artificial intelligence Machine learning, neural networks, language models, robotics, alignment and safety.
- 4070 Information and systems science Information theory, cybernetics, network theory, complexity, systems thinking. The theory of organising knowledge; the practice of keeping notes is 5030.
5000 Applied science and practice
- 5010 Agriculture and food Agronomy, horticulture, animal husbandry, aquaculture, forestry practice, food science, cooking.
- 5020 Architecture and design Built environment, urban planning, interiors, industrial and product design, typography, interface design.
- 5030 Education and learning Pedagogy, curriculum, assessment, educational psychology, and self-directed study.
- 5040 Engineering and technology Mechanical, electrical, civil, chemical, materials, and manufacturing engineering. Software engineering is 4050.
- 5050 Medicine and health Anatomy, pathology, pharmacology, clinical practice, nursing, public health, mental health treatment.
- 5060 Business and management Strategy, operations, entrepreneurship, org design, people management, accounting, governance. Practice; economic theory is 2050.
- 5070 Law and jurisprudence Constitutional, criminal, civil, contract, intellectual property, and international law; legal theory and practice.
- 5080 Military and security Strategy, tactics, defence technology, logistics, intelligence, information security.
- 5090 Environment and sustainability Conservation, resource management, forestry policy, energy transition, climate policy. Managing nature; the science is 3060.
- 5100 Library and information practice Cataloguing, classification, archives, curation, museum studies, records management.
- 5110 Public administration and policy Governance, public management, service delivery, policy design and evaluation.
- 5120 Social work and human services Casework, community services, welfare, counselling practice.
- 5130 Sport and recreation Physical performance, training, coaching, kinesiology, leisure, games and play.
- 5140 Transport and logistics Transport systems, supply chain, mobility, freight, infrastructure operations.
- 5150 Home and personal management Household economics, personal organisation, productivity, focus, and time practice, consumer decisions. The psychology behind it is 2040.
What is deliberately not here
No sub-disciplines. Not because they are unimportant — the opposite: they are the rows most worth having and the rows least possible to write for someone else. Nutrition under medicine, sales under business, note-taking under education are all defensible, and none of them is canon. They are anchors a particular person's cards asked for.
So they are published separately, as one filer's worked example rather than as part of the list. Take this page as your skeleton, and let your own fourth digits arrive when cards ask for them. When a row is earned → See the author's 5 →
That the split is even possible is a finding, not a preference. Mapping the 2,576-entry academic outline onto this table reaches every one of the 46 disciplines above — and misses two of the author's sub-disciplines entirely, because the academy has no entry for note-taking or for selling. The canonical tier is exactly the tier the academy can account for. The full mapping →
Why the numbers stop at four digits
A positional scheme — one digit per level, all the way down — would need about eleven digits, because one level of the source outline fans out to 130 siblings. A Dewey-style block allocation fares no better: nine slots per level, and it fails at the second level immediately.
So the digits stop at the discipline, and depth is carried by an unbounded alternating suffix instead. That is the trade the scheme makes, and everything else follows from it — including the fact that you will never renumber. How an address is computed →