Evaluate > Continuity > Surface Continuity
Checks the positional, tangent plane, and curvature continuity between and inside surfaces.
Surface Continuity Options
Find
G0 Positional Continuity – Only check for gaps between surfaces (labeled with “P” symbols).
G1 Tangent Continuity – Check for gaps and tangent discontinuities (labeled with “T” symbols).
G2 Curvature Continuity – Check for gaps, tangent, and curvature discontinuities (labeled with “C” symbols)
To switch between G0 Position Continuity, G1 Tangent Continuity, and G2 Curvature Continuity on multiple instances of the Surface Continuity locator, use the Position, Tangent, or Curvature buttons in the viewport to switch between continuity types, or use the spacebar to cycle through them.
Check Spacing By
Arc Length – Check the continuity at equally spaced points along the surface, determined by the Distance Between Checks option.
# Per Span – Check the continuity at a number of points in each span equal to the value of the Fitting > Curve Fit Checkpoints option of the Preferences > Construction Options
window.
Distance Between Checks
The arc-length distance between continuity checks when using the Arc Length option.
This option only appears when Check Spacing By is Arc Length.
Display Options
Locator Persistence
If this option is checked on, the surface continuity indicators have the ability to become a persistent locator which updates with changes to the geometry.
Locator Persistence only takes effect if boundaries are explicitly selected by clicking them (not by selecting surfaces with a pick box or before selecting the tool).
Check Interior
If this option is checked on, continuity is checked and displayed along multiple-knot iso-parametric curves in the interior of the surface.
Show Max Labels
If this option is checked on, points of maximum positional, tangency angle and curvature deviation are shown. Note however that these labels only appear if part of the boundary has discontinuities (gaps, tangent or curvature breaks) that are out of tolerance.
Show Deviation
When checking positional continuity (G0 Positional Continuity), check this option to display a comb that shows positional deviation between two surfaces. You can use the 
to scale the comb and 
to edit the steps in the comb.
Show Edge Labels
If this option is checked on, indicators showing areas of discontinuities (“O”, “C” and “T” labels) are initially displayed along the boundaries. Red symbols indicate areas of maximum discontinuity. Blue symbols indicate areas of minimum discontinuity.
The labels are nor displayed if Show Comb is turned on.
Show Comb
Check on this option to see the comb lines for gaps, tangency breaks, and curvature breaks.
Auto Scale
This option only appears if Show Combs is on. When Auto Scale is checked (default), the scale of the deviation combs is automatically calculated to be proportional to the size of the object.
When this option is unchecked, three Scale number fields appear (for Positional, Tangent, and Curvature deviation), allowing you to set the scales of the comb at the time of creation.
Scale
Three values (for Positional, Tangent, and Curvature deviation respectively) that allow you to adjust the scale of the combs at the time of creation. These values are only available if Auto Scale is turned off.