# USDLayer.Spec.FieldCollection Low-level read/write access to spec fields. Fields are the raw data backing both metadata and structural information on a spec. ``` protocol FieldCollection ``` ## Topics ### Instance Properties [`var fields: [USDToken]`](/documentation/USDKit/USDLayer/Spec/FieldCollection/fields) All authored field names on this spec. ### Instance Methods [`func clearField(USDToken) -> Bool`](/documentation/USDKit/USDLayer/Spec/FieldCollection/clearField(_:)) Clears the authored value for `name`. [`func field(USDToken) -> USDValue?`](/documentation/USDKit/USDLayer/Spec/FieldCollection/field(_:)) Returns the value of `name`, or `nil` if the field is unauthored. [`func field(USDToken, as: T.Type) -> T?`](/documentation/USDKit/USDLayer/Spec/FieldCollection/field(_:as:)) Typed field accessor. [`func isInert(ignoringChildren: Bool) -> Bool`](/documentation/USDKit/USDLayer/Spec/FieldCollection/isInert(ignoringChildren:)) Returns a Boolean value that indicates whether the spec contains no authored data. [`func setField(USDToken, to: USDValue) -> Bool`](/documentation/USDKit/USDLayer/Spec/FieldCollection/setField(_:to:)-26nys) Sets the field `name` to `value`. [`func setField(USDToken, to: T) -> Bool`](/documentation/USDKit/USDLayer/Spec/FieldCollection/setField(_:to:)-4lcqw) Typed field setter. ## Relationships ### Conforming Types [`PseudoRootSpec`](/documentation/USDKit/USDPrim/PseudoRootSpec) [`Spec`](/documentation/USDKit/USDPrim/Property/Spec) [`Spec`](/documentation/USDKit/USDPrim/Relationship/Spec) [`Spec`](/documentation/USDKit/USDLayer/Spec) [`VariantSpec`](/documentation/USDKit/USDPrim/VariantSpec) [`VariantSetSpec`](/documentation/USDKit/USDPrim/VariantSetSpec) [`Spec`](/documentation/USDKit/USDPrim/Spec) [`Spec`](/documentation/USDKit/USDPrim/Attribute/Spec) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)