System functions: Rework pages for individual system functions

Please speak with Fi before starting any of these.

Sub-tasks:

- [ ] `⎕`:
- Quad (quad.md)
- Evaluated Input (quad-input.md)
- Standard Output (quad-output.md)
- [ ] `⍞`:
- Quote Quad (quotequad.md)
- Character Input (quotequad-input.md)
- Message Output (quotequad-output.md)
- [ ] `⎕A`: Uppercase Alphabet (a.md)
- [ ] `⎕Ⓐ` or `⎕Á`: Underscored Uppercase Alphabet (underscored-alphabetic-characters.md)
- [ ] `⎕AI`: Account Information (ai.md)
- [ ] `⎕AN`: Account Name (an.md)
- [ ] `⎕ARBIN`: Arbitrary Input (arbin.md)
- [ ] `⎕ARBOUT`: Arbitrary Output (arbout.md)
- [ ] `⎕AT`: → #1107
- Object Attributes (at.md)
- Object Attributes for Dyalog (at-monadic.md)
- Object Attributes for APL2 (at-dyadic.md)
- [ ] `⎕ATX`: Extended Object Attributes (atx.md)
- [ ] `⎕AV`: Atomic Vector (av.md)
- [ ] `⎕AVU`: Atomic Vector Unicode Mapping (avu.md)
- [ ] `⎕BASE`: Base Class (base.md)
- [ ] `⎕C`: Case Convert (c.md)
- [ ] `⎕CLASS`:
- Class (class.md)
- Class Hierarchy (class-monadic.md)
- Get Class/Interface Implementation (class-dyadic.md)
- [ ] `⎕CLEAR`: Clear Workspace (clear.md)
- [ ] `⎕CMD`:
- Windows Processor (cmd.md)
- Call Windows Command Processor (cmd-monadic.md)
- Start Windows Auxiliary Processor (cmd-dyadic.md)
- [ ] `⎕CR`: Canonical Representation of Function (cr.md)
- [ ] `⎕CS`: Change Namespace (cs.md)
- [ ] `⎕CSV`:
- CSV (csv.md)
- Import CSV (csv-monadic.md)
- Export CSV (csv-dyadic.md)
- [ ] `⎕CT`: Comparison Tolerance (ct.md)
- [ ] `⎕CY`: Copy Objects from Workspace (cy.md)
- [ ] `⎕D`: Digits (d.md)
- [ ] `⎕DCT`: Decimal Comparison Tolerance (dct.md)
- [ ] `⎕DF`: Display Format (df.md)
- [ ] `⎕DIV`: Division Behaviour (div.md)
- [ ] `⎕DL`: Delay (dl.md)
- [ ] `⎕DM`: Diagnostic Message (dm.md)
- [ ] `⎕DMX`: Extended Diagnostic Message (dmx.md)
- [ ] `⎕DQ`: Dequeue and Process Events (dq.md)
- [ ] `⎕DR`:
- Data Representation (dr.md)
- Query Data Representation (dr-monadic.md)
- Transform Data Representation (dr-dyadic.md)
- [ ] `⎕DT`: Datetime (dt.md) → #1109
- [ ] `⎕ED`: Edit Objects (ed.md)
- [ ] `⎕EM`: Event Messages (em.md)
- [ ] `⎕EN`: Event Number (en.md)
- [ ] `⎕EX`: Expunge Objects (ex.md)
- [ ] `⎕EXCEPTION`: .NET Exception (exception.md)
- [ ] `⎕EXPORT`:
- Export Type (export.md)
- Query Export Type (export-monadic.md)
- Set Export Type (export-dyadic.md)
- [ ] `⎕FAPPEND`: Append Component to File (fappend.md)
- [ ] `⎕FAVAIL`: Component File System Availability (favail.md)
- [ ] `⎕FCHK`: Check/Repair Component File (fchk.md)
- [ ] `⎕FCOPY`: Copy Component File (fcopy.md)
- [ ] `⎕FCREATE`: Create Component File (fcreate.md)
- [ ] `⎕FDROP`: Drop Components (fdrop.md)
- [ ] `⎕FERASE`: Erase Component File (ferase.md)
- [ ] `⎕FHIST`: Component File History (fhist.md)
- [ ] `⎕FHOLD`: Component File Hold (fhold.md)
- [ ] `⎕FIX`: Define (fix.md)
- [ ] `⎕FLIB`: List Component Files (flib.md)
- [ ] `⎕FMT`:
- Format (fmt.md)
- Resolve Display Format (fmt-monadic.md)
- Format Array (fmt-dyadic.md)
- [ ] `⎕FNAMES`: Tied Component File Names (fnames.md)
- [ ] `⎕FNUMS`: Component File Tie Numbers (fnums.md)
- [ ] `⎕FPROPS`: Component File Properties (fprops.md)
- [ ] `⎕FR`: Floating-Point Representation (fr.md)
- [ ] `⎕FRDAC`: Read File Access Matrix (frdac.md)
- [ ] `⎕FRDCI`: Read Component Information (frdci.md)
- [ ] `⎕FREAD`: Read Component (fread.md)
- [ ] `⎕FRENAME`: Rename Component File (frename.md)
- [ ] `⎕FREPLACE`: Replace Component (freplace.md)
- [ ] `⎕FRESIZE`:
- Compact/Resize Component File (fresize.md)
- Compact Component File (fresize-monadic.md)
- Resize Component File (fresize-dyadic.md)
- [ ] `⎕FSIZE`: Component File Size (fsize.md)
- [ ] `⎕FSTAC`: Set Component File Access Matrix (fstac.md)
- [ ] `⎕FSTIE`: Share-Tie Component File (fstie.md)
- [ ] `⎕FTIE`: Exclusive-Tie Component File (ftie.md)
- [ ] `⎕FUNTIE`: Untie Component Files (funtie.md)
- [ ] `⎕FX`: Define Functions (fx.md)
- [ ] `⎕INSTANCES`: Instances (instances.md)
- [ ] `⎕IO`: Index Origin (io.md)
- [ ] `⎕JSON`:
- JSON (json.md)
- Import JSON (json-import.md)
- Export JSON (json-export.md)
- [ ] `⎕KL`: Key Labels (kl.md)
- [ ] `⎕LC`: Line Counter (lc.md)
- [ ] `⎕LOAD`: Load Workspace (load.md)
- [ ] `⎕LOCK`: Lock Function (lock.md)
- [ ] `⎕LX`: Latent Expression (lx.md)
- [ ] `⎕MAP`:
- Map File (map.md)
- Map Array File (map-monadic.md)
- Map Raw Data File (map-dyadic.md)
- [ ] `⎕MKDIR`: Create Directory (mkdir.md) → #1121
- [ ] `⎕ML`: Migration Level (ml.md)
- [ ] `⎕MONITOR`:
- Monitor Controls (monitor.md)
- Query Monitor Controls (monitor-monadic.md)
- Set Monitor Controls (monitor-dyadic.md)
- [ ] `⎕NA`: Associate External Function (na.md)
- [ ] `⎕NAPPEND`: Append to Native File (nappend.md)
- [ ] `⎕NC`: Name Classification (nc.md)
- [ ] `⎕NCOPY`: Copy Native Files/Directories (ncopy.md)
- [ ] `⎕NCREATE`: Create Native File (ncreate.md)
- [ ] `⎕NDELETE`: Delete Native File (ndelete.md)
- [ ] `⎕NERASE`: Erase Native File (nerase.md)
- [ ] `⎕NEW`: Create New Instance (new.md)
- [ ] `⎕NEXISTS`: Query Native File Existence (nexists.md)
- [ ] `⎕NGET`: Get Text File (nget.md)
- [ ] `⎕NINFO`: Native File Information (ninfo.md)
- [ ] `⎕NL`: List Object Names (nl.md)
- [ ] `⎕NLOCK`: Lock Native File (nlock.md)
- [ ] `⎕NMOVE`: Move Files/Directories (nmove.md)
- [ ] `⎕NNAMES`: Tied Native File Names (nnames.md)
- [ ] `⎕NNUMS`: Native Files Tie Numbers (nnums.md)
- [ ] `⎕NPARTS`: File Name Parts (nparts.md)
- [ ] `⎕NPUT`: Write Text File (nput.md)
- [ ] `⎕NQ`: Enqueue Event (nq.md)
- [ ] `⎕NR`: Nested Representation of Function (nr.md)
- [ ] `⎕NREAD`: Read from Native File (nread.md)
- [ ] `⎕NRENAME`: Rename Native File (nrename.md)
- [ ] `⎕NREPLACE`: Replace Native File Data (nreplace.md)
- [ ] `⎕NRESIZE`: Resize Native File (nresize.md)
- [ ] `⎕NS`: Create/Clone Namespace (ns.md)
- [ ] `⎕NSI`: State Indicator Namespace Names (nsi.md)
- [ ] `⎕NSIZE`: Native File Size (nsize.md)
- [ ] `⎕NTIE`: Exclusive-Tie Native File (ntie.md)
- [ ] `⎕NULL`: Null Item (null.md)
- [ ] `⎕NUNTIE`: Untie Native Files (nuntie.md)
- [ ] `⎕NXLATE`:
- Native File Translation Vector (nxlate.md)
- Query Native File Translation Vector (nxlate-monadic.md)
- Set Native File Translation Vector (nxlate-dyadic.md)
- [ ] `⎕OFF`: End Session (off.md)
- [ ] `⎕OPT`: Set Variant Options (opt.md)
- [ ] `⎕OR`: Object Representation (or.md)
- [ ] `⎕PATH`: Search Path (path.md)
- [ ] `⎕PFKEY`:
- Programmable Function Key (pfkey.md)
- Query Programmable Function Key (pfkey-monadic.md)
- Set Programmable Function Key (pfkey-dyadic.md)
- [ ] `⎕PP`: Print Precision (pp.md)
- [ ] `⎕PROFILE`:
- Profiling Overview (profile.md)
- `⎕PROFILE'start'`: Start Profiling (profile-start.md)
- `⎕PROFILE'stop'`: Stop Profiling (profile-stop.md)
- `⎕PROFILE'clear'`: Clear Profiling Data (profile-clear.md)
- `⎕PROFILE'calibrate'`: Calibrate Profiling Timer (profile-calibrate.md)
- `⎕PROFILE'state'`: Query Profiling State (profile-state.md)
- `⎕PROFILE'data'`: Get Flat Profiling Data (profile-data.md)
- `⎕PROFILE'tree'`: Get Profiling Data Tree (profile-tree.md)
- [ ] `⎕PW`: Print Width (pw.md)
- [ ] `⎕R`: Replace (r.md)
- [ ] `⎕REFS`: Local References (refs.md)
- [ ] `⎕RL`: Random Link (Seed) (rl.md)
- [ ] `⎕RSI`: State Indicator Namespace References (rsi.md)
- [ ] `⎕RTL`: Response Time Limit (rtl.md)
- [ ] `⎕S`: Search (s.md)
- [ ] `⎕SAVE`: Save Workspace (save.md)
- [ ] `⎕SD`: Query Screen Dimensions (sd.md)
- [ ] `⎕SE`: Session Namespace (se.md)
- [ ] `⎕SH`:
- Unix Processor (sh.md)
- Call Unix Command Processor (sh-monadic.md)
- Start Unix Auxiliary Processor (sh-dyadic.md)
- [ ] `⎕SHADOW`: Shadow Names (shadow.md)
- [ ] `⎕SHELL`: Call Shell or External Program (shell.md)
- [ ] `⎕SI`: State Indicator (si.md)
- [ ] `⎕SIGNAL`:
- Signal Event (signal.md) — `⎕SIGNAL 0` and `⎕SIGNAL emptyVector` and explaining that only `⊃Y` is used
- Signal Default Event (signal-default.md) — `⊃Y` is an integer and `X` is optional
- Signal Extended Event (signal-extended.md) — `⊃Y` is a vector of name-value pairs
- [ ] `⎕SIZE`: Query Object Sizes (size.md)
- [ ] `⎕SM`: Screen Map (sm.md)
- [ ] `⎕SR`: Screen Read (sr.md)
- [ ] `⎕SRC`: Object Source (src.md)
- [ ] `⎕STACK`: Execution Stack (stack.md)
- [ ] `⎕STATE`: Query Name State (state.md)
- [ ] `⎕STOP`:
- Stop Vector (stop.md)
- Query Stop Vector (stop-monadic.md)
- Set Stop Vector (stop-dyadic.md)
- [ ] `⎕SVC`:
- Shared Variable Access Control (svc.md)
- Query Shared Variable Access Control (svc-monadic.md)
- Set Shared Variable Access Control (svc-dyadic.md)
- [ ] `⎕SVO`:
- Shared Variable Offer (svo.md)
- Query Shared Variable Degree of Coupling (svo-monadic.md)
- Offer Shared Variable (svo-dyadic.md)
- [ ] `⎕SVQ`: Query Shared Variable (svq.md)
- [ ] `⎕SVR`: Retract Shared Variable Offer (svr.md)
- [ ] `⎕SVS`: Query Shared Variable State (svs.md)
- [ ] `⎕SYSTEM`: System Information (system.md)
- [ ] `⎕TALLOC`:
- Token Allocation (talloc.md)
- `⎕TALLOC 1 Y`: Allocate Token Range (talloc-allocate.md)
- `X ⎕TALLOC ¯1`: De-allocate Token Range (talloc-deallocate.md)
- `{X} ⎕TALLOC 0`: Query Allocated Token Ranges (talloc-ranges.md)
- `X ⎕TALLOC 2`: Query Pooled Tokens in Range (talloc-pool.md)
- [ ] `⎕TC`: Terminal Control (tc.md)
- [ ] `⎕TCNUMS`: Thread Child Numbers (tcnums.md)
- [ ] `⎕TGET`: Get Tokens (tget.md)
- [ ] `⎕THIS`: Current Namespace (this.md)
- [ ] `⎕TID`: Current Thread Identity (tid.md)
- [ ] `⎕TKILL`: Kill Threads (tkill.md)
- [ ] `⎕TNAME`: Current Thread Name (tname.md)
- [ ] `⎕TNUMS`: Thread Numbers (tnums.md)
- [ ] `⎕TPOOL`: Token Pool (tpool.md)
- [ ] `⎕TPUT`: Put Tokens (tput.md)
- [ ] `⎕TRACE`:
- Trace Vector (trace.md)
- Query Trace Vector (trace-monadic.md)
- Set Trace Vector (trace-dyadic.md)
- [ ] `⎕TRAP`: Event Trap (trap.md)
- [ ] `⎕TREQ`: Token Requests (treq.md)
- [ ] `⎕TS`: Current Timestamp (ts.md)
- [ ] `⎕TSYNC`: Synchronise Threads (tsync.md)
- [ ] `⎕UCS`:
- Convert Unicode (ucs.md)
- Convert Unicode Code Point (ucs-monadic.md)
- Convert Unicode Representation (ucs-dyadic.md)
- [ ] `⎕USING`: .NET Search Path (using.md)
- [ ] `⎕VFI`: Parse Numbers (vfi.md)
- [ ] `⎕VGET`: Get Value (vget.md)
- [ ] `⎕VR`: Vector Representation of Function (vr.md)
- [ ] `⎕VSET`: Set Value (vset.md)
- [ ] `⎕WA`: Workspace Available (wa.md)
- [ ] `⎕WC`: Create GUI Object (wc.md)
- [ ] `⎕WG`: Get GUI Object Properties (wg.md)
- [ ] `⎕WN`: Get GUI Child Names (wn.md)
- [ ] `⎕WS`: Set GUI Object Properties (ws.md)
- [ ] `⎕WSID`: Workspace Identification (wsid.md)
- [ ] `⎕WX`: Expose GUI Properties (wx.md)
- [ ] `⎕XML`:
- XML (xml.md)
- Import XML (xml-import.md)
- Export XML (xml-export.md)
- [ ] `⎕XSI`: Extended State Indicator (xsi.md)
- [ ] `⎕XT`:
- External Variable (xt.md)
- Query External Variable (xt-monadic.md)
- Associate External Variable (xt-dyadic.md)