Revision as of 16:14, 15 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.

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	Supporting rulesRelated guidance for modifiers and datum systems.

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 forumAnnouncements, questions, feature requests, and showcases.

MessagesDirect messages between contributors.

Contribute

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+| [[Category:GDT Reference|<span class="f4-card-link"><span class="f4-card-title">GD&T Reference</span><span class="f4-card-desc">Standard definitions, symbols, and usage guidance.</span></span>]]
-<div class="f4-card-title">[[Category:GDT Reference|GD&T Reference]]</div>
+| [[Category:F4 Behavior|<span class="f4-card-link"><span class="f4-card-title">F4 Behavior</span><span class="f4-card-desc">Rules, checks, and decisions used by the F4 validator.</span></span>]]
-<div class="f4-card-desc">Standard definitions, symbols, and usage guidance.</div>
+| [[Category:Glossary|<span class="f4-card-link"><span class="f4-card-title">Glossary and Examples</span><span class="f4-card-desc">Short definitions and worked applications.</span></span>]]
-| class="f4-card" |
-<div class="f4-card-title">[[Category:F4 Behavior|F4 Behavior]]</div>
-<div class="f4-card-desc">Rules, checks, and decisions used by the F4 validator.</div>
-| class="f4-card" |
-<div class="f4-card-title">[[Category:Glossary|Glossary and Examples]]</div>
-<div class="f4-card-desc">Short definitions and worked applications.</div>
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 {| class="f4-card-grid"
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+| [[Category:Form|<span class="f4-card-link"><span class="f4-card-title">Form</span><span class="f4-card-desc">Straightness, flatness, circularity, cylindricity.</span></span>]]
-<div class="f4-card-title">[[Category:Form|Form]]</div>
+| [[Category:Orientation|<span class="f4-card-link"><span class="f4-card-title">Orientation</span><span class="f4-card-desc">Parallelism, perpendicularity, angularity.</span></span>]]
-<div class="f4-card-desc">Straightness, flatness, circularity, cylindricity.</div>
-| class="f4-card" |
-<div class="f4-card-title">[[Category:Orientation|Orientation]]</div>
-<div class="f4-card-desc">Parallelism, perpendicularity, angularity.</div>
 |-
-| class="f4-card" |
+| [[Category:Location|<span class="f4-card-link"><span class="f4-card-title">Location</span><span class="f4-card-desc">Position, composite, MSS, concentricity, symmetry.</span></span>]]
-<div class="f4-card-title">[[Category:Location|Location]]</div>
+| [[Category:Profile|<span class="f4-card-link"><span class="f4-card-title">Profile</span><span class="f4-card-desc">Line, surface, composite, MSS.</span></span>]]
-<div class="f4-card-desc">Position, composite, MSS, concentricity, symmetry.</div>
-| class="f4-card" |
-<div class="f4-card-title">[[Category:Profile|Profile]]</div>
-<div class="f4-card-desc">Line, surface, composite, MSS.</div>
 |-
-| class="f4-card" |
+| [[Category:Runout|<span class="f4-card-link"><span class="f4-card-title">Runout</span><span class="f4-card-desc">Circular and total runout.</span></span>]]
-<div class="f4-card-title">[[Category:Runout|Runout]]</div>
+| <span class="f4-card-link"><span class="f4-card-title">Supporting rules</span><span class="f4-card-desc">Related guidance for modifiers and datum systems.</span><span class="f4-card-links">[[Category:Modifiers|<span class="f4-pill">Modifiers</span>]] [[Category:Datums|<span class="f4-pill">Datums</span>]]</span></span>
-<div class="f4-card-desc">Circular and total runout.</div>
-| class="f4-card" |
-<div class="f4-card-title">Supporting rules</div>
-<div class="f4-card-desc">[[Category:Modifiers|Modifiers]] and [[Category:Datums|Datums]].</div>
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+| [[Forum:Start|<span class="f4-card-link"><span class="f4-card-title">Community forum</span><span class="f4-card-desc">Announcements, questions, feature requests, and showcases.</span></span>]]
-<div class="f4-card-title">[[Forum:Start|Community forum]]</div>
+| [[Special:UserBoard|<span class="f4-card-link"><span class="f4-card-title">Messages</span><span class="f4-card-desc">Direct messages between contributors.</span></span>]]
-<div class="f4-card-desc">Announcements, questions, feature requests, and showcases.</div>
-| class="f4-card" |
-<div class="f4-card-title">[[Special:UserBoard|Messages]]</div>
-<div class="f4-card-desc">Direct messages between contributors.</div>
 |}