This article will review each option and what it is used for.
Write
The MSBO (Manifold Solid B-rep Objects) option toggles the exporting of parts as MSBO's or trimmed faces without connectivity information for IGES version 4.0
The AutoCAD faces option toggles the ability to export an IGES file specifically for use with AutoCAD
The JAMA-IS v1.04 Spec. option toggles the ability to export IGES files using a subset of the IGES v5.0 specification which accepts the JAMA convention of not supporting certain constraints as well as MSBO entities
The Wire as copious data option toggles the ability to write a wire as copious data (entity #106, form 12) instead of separate curves
The Trimmed curves option toggles the ability to write trimmed curves as 2D parametric curves with trimmed curve preference for 2D data which is required when writing IGES files for CATIA
The Trim surfaces as NURBS (Non-Uniform Rational B-Splines) option toggles the ability to specify that all surfaces be converted to NURBs and written as IGESNURBs surfaces (Entity #128)
The Ellipses as NURBS option toggles the ability to specify that all ellipses be converted to NURBs and written as IGESNURBs surfaces (Entity #128)
The Bounded surfaces option toggles the ability to write all surfaces as bounded which is useful for writing IGES for CATIA as CATIA requires that all surfaces be bounded, otherwise surfaces will be written as trimmed whenever possible
The EOL length: option specifies the length of the end-of-line character (in bytes) required for an operating system between the 1, 2, 3 and 4 options
The Represent model in: option selects the unit of measurement to export a model from the Millimeters, Centimeters, Meters, Inches and Feet options
Read
The Free curves option toggles the conversion of free curves into corresponding ACIS edges
The Free points option toggles the conversion of point entities into corresponding ACIS point entities
The Free surfaces option toggles the conversion of free face entities into corresponding ACIS face entities
The Copious data curve option toggles the conversion of copious data curves (polyline curves) into multiple ACIS curves, otherwise a conversion will output multiple ACIS curves which can allow data explosion to occur
The Scale to mm option toggles the scaling of IGES files to millimeters
The Spline curve edges split option toggles the production of vertices at the cusps of spline curves
The Scale factor: option sets the conversion of scale factors to units other than millimeters and once set it will set the standard for all successive imports
The Points to evaluate during conversion option sets a value for controlling the number of points to be evaluated per knot span during the conversion of a 2D curve to a 3D curve with a negative value creating an automatic determination based on the degree of a 2D curve and a positive value setting the evaluation of the number of points
The Tolerance for breaking curves into edges option sets a value for breaking curves into edges for specifying the tolerance used for breaking curves into separate edges
The Trimmed curve preferences: option selects how to read trimmed curves from Unspecified which reads trimmed curves as individual preferences given in a IGES file, 2D curve which uses 2D parametric data for all trimming curves, or 3D curve which uses 3D data for all trimming curves