Here's a list of the features provided by different kinds of standard and proposed record systems. The specific syntax of syntax forms and the exact calling conventions of procedures is ignored here.

Glossary:

• A record constructor is a procedure that constructs a record of a specified type
• A record accessor is a procedure that gets the value of a particular element of a record
• A record mutator is a procedure that sets the value of a particular element of a record
• A record predicate is a procedure that returns #t or #f depending on whether its argument is an instance of a given record type

• An RTD (record-type-descriptor) is a run-time object representing a record type.

Features:

• [SyntacticRecords Syntactic] means record types are specified by one or more macros that bind identifiers to record types, constructors, accessors, mutators, and predicates.
• ''Procedural'' means that record types are created by a procedure which returns an RTD, and that by applying other procedures to the RTD, constructors, accessors, mutators, and predicates are returned

• [GenerativeRecords Generative] record types are unique in each definition
• [NonGenerativeRecords Non-generative] record types have a uid (a symbol) and are identical if they share the same symbol

• A ''natural constructor'' is a procedure whose arguments correspond to the fields of the record in the order they were specified when creating the RTD
• A ''filtering constructor'' is a procedure whose arguments correspond to some of the fields of the record in an order which may or may not be the specification order.
• A ''generalized constructor'' is one which applies an arbitrary procedure, called the protocol procedure, that transforms its arguments in any way desired and then calls a natural constructor.
• A ''label constructor'' is one which maps field labels to values independent of order.

Standards

(srfi 9) is syntactic. It provides:

• Distinct types
• Opaque RTD bindings with no interface
• A single filtering constructor
• Mutable fields
• Immutable fields
• Generative records
• Top-level definitions only

(srfi 57) is syntactic. It extends (srfi 9) as follows:

• Multiple interface inheritance
• A label constructor
• Record composition
• Functional record update
• In-place record update

(srfi 99 records syntactic) is syntactic. It extends (srfi 9) as follows:

• Record definitions appear where other definitions appear
• Single inheritance
• A default natural constructor when the constructor parameters are unspecified
• Auto-generated non-hygienic names

(rnrs records syntactic 6) is syntactic. It extends (srfi 99 records syntactic) as follows:

• Generalized constructor
• Sealed RTDs from which other RTDs cannot inherit (optional in SRFI-99)
• Opaque RTDs that create records that don't satisfy RECORD? (optional in SRFI-99)
• Non-generative RTDs (optional in SRFI-99)

(srfi 99 records procedural) is procedural. It extends (srfi 99 records syntactic) as follows:

• RTDs have names (symbols)
• Procedure to create an RTD
• Procedure to create natural and filtering constructors from an RTD
• Procedure to create predicates from an RTD
• Procedure to create accessors and mutators from an RTD and a field name

(srfi 99 records inspection) is procedural. It provides the following:

• Predicate that returns #t on any record
• Procedure to extract RTD from a record
• Procedures to access name, parent, field names, inherited field names from an RTD

(rnrs records procedural 6) is procedural. It extends (rnrs records syntactic 6) as follows:

• Procedure to create an RTD
• Procedure to create a constructor-descriptor (which can then create a constructor) for natural and generalized constructors from an RTD
• Procedure to create predicates from an RTD
• Procedure to create accessors and mutators from an RTD and a field index (doesn't work for inherited fields)

(rnrs records inspection 6) is procedural. It extends (srfi 99 records inspection) as follows:

• Procedures to extract sealedness, opaqueness, and nongenerative id from an RTD; these are optional in SRFI-99

RecordsArcfide is syntactic. It extends SRFI 9 as follows:

• Single inheritance (with multiple inheritance as possible future extension)

AggregatesMedernach is procedural. It provides:

• Distinct types
• Natural constructor
• Mutable fields
• Generative records
• An accessor that applies a procedure to the fields in the record

UserAggregatesRush is procedural. It provides:

• Distinct types
• Subtype/supertype predicates
• Universal constructors/predicate/accessors/mutators that require a RTD argument
• Natural constructors that specify the number of fields
• Mutable fields
• No inheritance, only subtyping
• Generative records

UniqueTypesSnellPym is procedural. It provides:

• Distinct types
• No RTD objects; type constructor returns procedures directly
• A single filtering constructor
• Immutable fields
• Generative and non-generative records
• Single inheritance (optional proposal)
• Mutable fields (optional proposal)

Issues and Discussions

• EfficiencyConcerns
• InterfaceComparison

Eventually there should be a companion page for native record systems provided by individual Schemes.