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Package 1 — Basic Types

Package 1 defines the foundational value types used throughout the data model: identification metadata, unit references, special numeric values, nil sentinels, and constraint types.

AbstractSWE

The root base type for all SWE Common objects (other than value objects). It carries a single optional id field — a URI fragment identifier that makes the object referenceable.

struct AbstractSWE {
  id @0 :Text;
}

table AbstractSWE {
  id:string;
}

message AbstractSWE {
  string id = 1;
}

AbstractSWEIdentifiable

Extends AbstractSWE with human-readable metadata. Most concrete types embed this (via their AbstractDataComponent base) to carry a label and description.

Field Type Description
base AbstractSWE Inherited id
label string Short human-readable name
description string Longer explanation

UnitReference

A reference to a unit of measure. Typically you'll set the code field to a UCUM code (e.g., "Cel" for Celsius, "m/s" for meters per second). The href field can point to a full unit definition URI when UCUM doesn't cover your needs.

Field Type Description
label string Human-readable unit name
symbol string Display symbol (e.g., "°C")
code string UCUM code
href string URI to unit definition

NumberOrSpecial

A numeric value that can also represent IEEE-754 special values. This is the building block for constraint ranges and Quantity values.

Uses a native unnamed union:

struct NumberOrSpecial {
  union {
    number @0 :Float64;
    nan    @1 :Void;
    posInf @2 :Void;
    negInf @3 :Void;
  }
}

Uses an enum discriminator with separate fields (FlatBuffers tables cannot union scalars and strings inline):

enum NumberOrSpecialKind : byte { Number = 0, NaN, PosInf, NegInf }
table NumberOrSpecial {
  kind:NumberOrSpecialKind = Number;
  number:double;
}

Uses a oneof:

message NumberOrSpecial {
  oneof value {
    double number = 1;
    bool nan = 2;
    bool pos_inf = 3;
    bool neg_inf = 4;
  }
}

DateTimeOrNumber

Similar to NumberOrSpecial but adds an ISO-8601 date-time string variant. Used by Time components and temporal constraints.

The union variants are: dateTime (ISO-8601 string), number (Float64), nan, posInf, negInf.

Nil values

Nil value types define sentinel values that stand in for "no data" along with a reason URI explaining why. There are four variants matching the value domains of the scalar components:

Type Value field type Used by
NilValueText string Text, Category
NilValueInteger int64 Count
NilValueNumber NumberOrSpecial Quantity
NilValueTime DateTimeOrNumber Time

Each carries a reason field (URI) and a value field with the sentinel.

Constraints

Constraint types restrict the domain of valid values for a component.

AllowedValues

Constrains numeric values by enumeration and/or inclusive intervals. Used by Count, Quantity, and their range counterparts.

Field Type Description
values list of NumberOrSpecial Enumerated permitted values
intervals list of NumberInterval Inclusive [low, high] ranges
significantFigures uint8 Precision (1–40; 0 = unset)

AllowedTokens

Constrains string values by enumeration or regex pattern. Used by Text and Category.

Uses an unnamed union — either a list of values or a regex pattern:

struct AllowedTokens {
  union {
    values  @0 :List(Text);
    pattern @1 :Text;
  }
}

Uses an enum discriminator (AllowedTokensKind) because FlatBuffers can't union a vector with a scalar.

Proto3 oneof cannot contain repeated fields, so a nested TokenList message wraps the string list:

message AllowedTokens {
  message TokenList {
    repeated string values = 1;
  }
  oneof constraint {
    TokenList value_list = 1;
    string pattern = 2;
  }
}

AllowedTimes

Same structure as AllowedValues but over the DateTimeOrNumber domain. Used by Time and TimeRange.

AssociationAttributeGroup

An XLink-style by-reference association used throughout the model to point to external resources (e.g., out-of-band stream values, referenced components).

Field Type Description
href string URI-reference (required)
role string URI describing the role
arcrole string URI describing the arc role
title string Human-readable title