Revision as of 23:50, 14 January 2026

F4 Wiki

The public, stable reference for GD&T and how the F4 Application interprets it. Each topic pairs standard GD&T guidance with F4 validation behavior so you can move from definition to decision quickly.

Quick links

Start here

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Standard definitions, symbols, and usage guidance.

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Rules, checks, and decisions used by the F4 validator.

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Short definitions and worked applications.

Browse by category

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Straightness, flatness, circularity, cylindricity.

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Parallelism, perpendicularity, angularity.

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Position, composite, MSS, concentricity, symmetry.

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Line, surface, composite, MSS.

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Circular and total runout.

Supporting rules

and .

Featured pages

GDT:Straightness - basic line element form control.
GDT:Flatness - planar form control.
GDT:Position - primary location control for features of size.
GDT:Profile of a Surface - shape and location combined.
F4:Position Validation - how F4 checks position.

How to use this wiki

The public view shows approved revisions only.
Each GD&T page links to its matching F4 validation page.
Use the sidebar or search to find topics quickly.
When a rule needs interpretation, the F4 page calls out the decision and its impact.

Community

Community forum

Announcements, questions, feature requests, and showcases.

Messages

Direct messages between contributors.

Contribute

@@ Line 1: / Line 1: @@
+<!-- Copy into Main Page -->
 __NOTOC__
 = F4 Wiki =
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+[[File:F4_Logo_White.svg|56px|alt=F4]]
-<htmltag tagname="div" style="display: flex; gap: 16px; align-items: center; flex-wrap: wrap;">
+''The public, stable reference for GD&T and how the F4 Application interprets it.''
-<htmltag tagname="div" style="flex: 0 0 auto;">
+Each topic pairs standard GD&T guidance with F4 validation behavior so you can move from definition to decision quickly.
-<htmltag tagname="img" src="/resources/assets/logo-white.svg" alt="F4" width="56" height="56" loading="lazy"></htmltag>
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-<htmltag tagname="div" style="font-size: 1.2em; font-weight: 600;">The public, stable reference for GD&T and how the F4 Application interprets it.</htmltag>
-<htmltag tagname="div" style="margin-top: 0.4em; color: var(--f4-text-muted);">Each topic pairs standard GD&T guidance with F4 validation behavior so you can move from definition to decision quickly.</htmltag>
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-<htmltag tagname="a" href="https://f4.dev/" style="display: inline-block; padding: 6px 10px; border-radius: 8px; background: var(--f4-bg-surface); border: 1px solid var(--f4-border); color: var(--f4-text); text-decoration: none;">F4 website</htmltag>
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-</htmltag>
-</htmltag>
+== Quick links ==
+* [https://f4.dev/ F4 website]
+* [https://docs.f4.dev/ Documentation]
+* [https://download.f4.dev/ Downloads]
+== Start here ==
 {| style="width: 100%; border-collapse: separate; border-spacing: 12px;"
 |-
-| style="vertical-align: top; width: 33%;" |
+| style="vertical-align: top; width: 33%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
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+'''[[Category:GDT Reference|GD&T Reference]]'''
-<htmltag tagname="div" style="font-weight: 600;">GD&T Reference</htmltag>
+: Standard definitions, symbols, and usage guidance.
-<htmltag tagname="div" style="margin-top: 0.4em; color: var(--f4-text-muted);">Standard definitions, symbols, and usage guidance.</htmltag>
+| style="vertical-align: top; width: 33%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
-</htmltag>
+'''[[Category:F4 Behavior|F4 Behavior]]'''
-| style="vertical-align: top; width: 33%;" |
+: Rules, checks, and decisions used by the F4 validator.
-<htmltag tagname="a" href="/index.php/Category:F4_Behavior" style="display: block; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px; padding: 0.9em; text-decoration: none; color: var(--f4-text);">
+| style="vertical-align: top; width: 33%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
-<htmltag tagname="div" style="font-weight: 600;">F4 Behavior</htmltag>
+'''[[Category:Glossary|Glossary and Examples]]'''
-<htmltag tagname="div" style="margin-top: 0.4em; color: var(--f4-text-muted);">Rules, checks, and decisions used by the F4 validator.</htmltag>
+: Short definitions and worked applications.
-</htmltag>
-| style="vertical-align: top; width: 33%;" |
-<htmltag tagname="a" href="/index.php/Category:Glossary" style="display: block; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px; padding: 0.9em; text-decoration: none; color: var(--f4-text);">
-<htmltag tagname="div" style="font-weight: 600;">Glossary and Examples</htmltag>
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-<htmltag tagname="div" style="margin-top: 0.6em; color: var(--f4-accent);">Browse glossary and examples</htmltag>
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 |}
@@ Line 42: / Line 29: @@
 {| style="width: 100%; border-collapse: separate; border-spacing: 12px;"
 |-
-| style="vertical-align: top; width: 50%;" |
+| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
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+'''[[Category:Form|Form]]'''
-<htmltag tagname="div" style="font-weight: 600;">Form</htmltag>
+: Straightness, flatness, circularity, cylindricity.
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+| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
-</htmltag>
+'''[[Category:Orientation|Orientation]]'''
-| style="vertical-align: top; width: 50%;" |
+: Parallelism, perpendicularity, angularity.
-<htmltag tagname="a" href="/index.php/Category:Orientation" style="display: block; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px; padding: 0.9em; text-decoration: none; color: var(--f4-text);">
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-<htmltag tagname="div" style="margin-top: 0.4em; color: var(--f4-text-muted);">Parallelism, perpendicularity, angularity.</htmltag>
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 |-
-| style="vertical-align: top; width: 50%;" |
+| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
-<htmltag tagname="a" href="/index.php/Category:Location" style="display: block; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px; padding: 0.9em; text-decoration: none; color: var(--f4-text);">
+'''[[Category:Location|Location]]'''
-<htmltag tagname="div" style="font-weight: 600;">Location</htmltag>
+: Position, composite, MSS, concentricity, symmetry.
-<htmltag tagname="div" style="margin-top: 0.4em; color: var(--f4-text-muted);">Position, composite, MSS, concentricity, symmetry.</htmltag>
+| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
-</htmltag>
+'''[[Category:Profile|Profile]]'''
-| style="vertical-align: top; width: 50%;" |
+: Line, surface, composite, MSS.
-<htmltag tagname="a" href="/index.php/Category:Profile" style="display: block; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px; padding: 0.9em; text-decoration: none; color: var(--f4-text);">
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-<htmltag tagname="div" style="margin-top: 0.4em; color: var(--f4-text-muted);">Line, surface, composite, MSS.</htmltag>
-</htmltag>
 |-
-| style="vertical-align: top; width: 50%;" |
+| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
-<htmltag tagname="a" href="/index.php/Category:Runout" style="display: block; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px; padding: 0.9em; text-decoration: none; color: var(--f4-text);">
+'''[[Category:Runout|Runout]]'''
-<htmltag tagname="div" style="font-weight: 600;">Runout</htmltag>
+: Circular and total runout.
-<htmltag tagname="div" style="margin-top: 0.4em; color: var(--f4-text-muted);">Circular and total runout.</htmltag>
+| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
-</htmltag>
+'''Supporting rules'''
-| style="vertical-align: top; width: 50%;" |
+: [[Category:Modifiers|Modifiers]] and [[Category:Datums|Datums]].
-<htmltag tagname="div" style="background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px; padding: 0.9em;">
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 |}
@@ Line 92: / Line 67: @@
 {| style="width: 100%; border-collapse: separate; border-spacing: 12px;"
 |-
-| style="vertical-align: top; width: 50%;" |
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+'''[[Forum:Start|Community forum]]'''
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+: Announcements, questions, feature requests, and showcases.
-<htmltag tagname="div" style="margin-top: 0.4em; color: var(--f4-text-muted);">Announcements, questions, feature requests, and showcases.</htmltag>
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-</htmltag>
+'''[[Special:UserBoard|Messages]]'''
-| style="vertical-align: top; width: 50%;" |
+: Direct messages between contributors.
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-<htmltag tagname="div" style="font-weight: 600;">Messages</htmltag>
-<htmltag tagname="div" style="margin-top: 0.4em; color: var(--f4-text-muted);">Direct messages between contributors.</htmltag>
-</htmltag>
 |}