Revision as of 16:21, 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.

Quick links

Start here

GD&T Reference
Standard definitions, symbols, and usage guidance.

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

Glossary and Examples
Short definitions and worked applications.

Browse by category

Form
Straightness, flatness, circularity, cylindricity.

Orientation
Parallelism, perpendicularity, angularity.

Location
Position, composite, MSS, concentricity, symmetry.

Profile
Line, surface, composite, MSS.

Runout
Circular and total runout.

Supporting rules Related 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 forum
Announcements, questions, feature requests, and showcases.

Messages
Direct messages between contributors.

@@ Line 1: / Line 1: @@
-<!-- Copy into Main Page -->
 __NOTOC__
 = F4 Wiki =
@@ Line 13: / Line 12: @@
 == Start here ==
-{| style="width: 100%; border-collapse: separate; border-spacing: 12px;"
+{| class="f4-card-grid"
 |-
-| style="vertical-align: top; width: 33%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
+| class="f4-card" |
-'''[[Category:GDT Reference|GD&T Reference]]'''
+'''[[:Category:GDT Reference|GD&T Reference]]'''<br/>
-: Standard definitions, symbols, and usage guidance.
+Standard definitions, symbols, and usage guidance.
-| style="vertical-align: top; width: 33%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
+| class="f4-card" |
-'''[[Category:F4 Behavior|F4 Behavior]]'''
+'''[[:Category:F4 Behavior|F4 Behavior]]'''<br/>
-: Rules, checks, and decisions used by the F4 validator.
+Rules, checks, and decisions used by the F4 validator.
-| style="vertical-align: top; width: 33%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
+| class="f4-card" |
-'''[[Category:Glossary|Glossary and Examples]]'''
+'''[[:Category:Glossary|Glossary and Examples]]'''<br/>
-: Short definitions and worked applications.
+Short definitions and worked applications.
 |}
 == Browse by category ==
-{| style="width: 100%; border-collapse: separate; border-spacing: 12px;"
+{| class="f4-card-grid"
 |-
-| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
+| class="f4-card" |
-'''[[Category:Form|Form]]'''
+'''[[:Category:Form|Form]]'''<br/>
-: Straightness, flatness, circularity, cylindricity.
+Straightness, flatness, circularity, cylindricity.
-| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
+| class="f4-card" |
-'''[[Category:Orientation|Orientation]]'''
+'''[[:Category:Orientation|Orientation]]'''<br/>
-: Parallelism, perpendicularity, angularity.
+Parallelism, perpendicularity, angularity.
 |-
-| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
+| class="f4-card" |
-'''[[Category:Location|Location]]'''
+'''[[:Category:Location|Location]]'''<br/>
-: Position, composite, MSS, concentricity, symmetry.
+Position, composite, MSS, concentricity, symmetry.
-| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
+| class="f4-card" |
-'''[[Category:Profile|Profile]]'''
+'''[[:Category:Profile|Profile]]'''<br/>
-: Line, surface, composite, MSS.
+Line, surface, composite, MSS.
 |-
-| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
+| class="f4-card" |
-'''[[Category:Runout|Runout]]'''
+'''[[:Category:Runout|Runout]]'''<br/>
-: Circular and total runout.
+Circular and total runout.
-| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
+| class="f4-card" |
 '''Supporting rules'''
-: [[Category:Modifiers|Modifiers]] and [[Category:Datums|Datums]].
+Related guidance for modifiers and datum systems.
+* [[:Category:Modifiers|Modifiers]]
+* [[:Category:Datums|Datums]]
 |}
@@ Line 65: / Line 66: @@
 == Community ==
-{| style="width: 100%; border-collapse: separate; border-spacing: 12px;"
+{| class="f4-card-grid"
 |-
-| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
+| class="f4-card" |
-'''[[Forum:Start|Community forum]]'''
+'''[[Forum:Start|Community forum]]'''<br/>
-: Announcements, questions, feature requests, and showcases.
+Announcements, questions, feature requests, and showcases.
-| style="vertical-align: top; width: 50%; padding: 0.9em; background: var(--f4-bg-panel); border: 1px solid var(--f4-border); border-radius: 10px;" |
+| class="f4-card" |
-'''[[Special:UserBoard|Messages]]'''
+'''[[Special:UserBoard|Messages]]'''<br/>
-: Direct messages between contributors.
+Direct messages between contributors.
 |}

Main Page: Difference between revisions