# Question regarding AllowedTokens
**URL:** https://forum.aousd.org/t/question-regarding-allowedtokens/1857
**Category:** USD
**Tags:** cpp
**Created:** [September 12, 2024, 1:01pm UTC](https://forum.aousd.org/t/question-regarding-allowedtokens/1857 "2024-09-12T13:01:05Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@hamed](https://forum.aousd.org/u/hamed)
#### Post date: [September 12, 2024, 1:01pm UTC](https://forum.aousd.org/t/question-regarding-allowedtokens/1857/1 "2024-09-12T13:01:05Z")
Hi,
Is there a significant difference between getting the allowedTokens meta data through UsdPrimDefinition vs directly from the attribute itself? If there is, when should I choose one over the other?
```auto
PXR_NS::VtTokenArray allowedTokens;
const PXR_NS::UsdPrimDefinition& primDef = prim.GetPrimDefinition();
primDef.GetPropertyMetadata(attr->GetName(),PXR_NS::SdfFieldKeys->AllowedTokens,&allowedTokens)
```
VS
```auto
PXR_NS::VtTokenArray allowedTokens;
attr.GetMetadata(PXR_NS::SdfFieldKeys->AllowedTokens,&allowedTokens)
```
---
### Author:  [@spiff](https://forum.aousd.org/u/spiff)
#### Post date: [September 19, 2024, 5:17am UTC](https://forum.aousd.org/t/question-regarding-allowedtokens/1857/2 "2024-09-19T05:17:42Z")
AllowedTokens on schema properties ideally would not be over rideable in scenes, since they are tied to coded schema behavior. So I’d recommend going to the PrimDefinition.
---
### Author:  [@hamed](https://forum.aousd.org/u/hamed)
#### Post date: [September 24, 2024, 8:34pm UTC](https://forum.aousd.org/t/question-regarding-allowedtokens/1857/3 "2024-09-24T20:34:16Z")
To be more clear, we do have some properties that are tied to our custom schema.
e.g
```auto
#usda 1.0
def Xform "root"
{
def Xform "dummy"
{
token foo:flags:preset = "Default" (
allowedTokens = ["Default", "A", "B", "C", "D"]
)
}
}
```
In my original approach ( code below ) I was only asking PrimDefinition to give me allowedTokens but in the case of above example, GetPropertyMetadata returns false.
```auto
PXR_NS::VtTokenArray allowedTokens;
const PXR_NS::UsdPrimDefinition& primDef = attrWrapper->usdPrim().GetPrimDefinition();
// returns true if a fallback value is defined for the given metadata
if (primDef.GetPropertyMetadata(attrWrapper->name(),PXR_NS::SdfFieldKeys->AllowedTokens,&allowedTokens)) {
// create an Enum Attribute from a list of allowed tokens
} else {
// create an Enum Attribute from the current value only
}
```
I think if I understand this correctly, I should first ask PrimDefinition and if that fails, then ask the metadata on the attribute to retrieve the allowedTokens. something like this:
```auto
PXR_NS::VtTokenArray allowedTokens;
const PXR_NS::UsdPrimDefinition& primDef = attrWrapper->usdPrim().GetPrimDefinition();
if (primDef.GetPropertyMetadata(attrWrapper->name(),PXR_NS::SdfFieldKeys->AllowedTokens,&allowedTokens)) {
// create an Enum Attribute from a list of allowed tokens
} else if (attrWrapper->usdAttribute().GetMetadata(PXR_NS::SdfFieldKeys->AllowedTokens, &allowedTokens)) {
// create an Enum Attribute from a list of allowed tokens tied to certain schema
}
else {
// create an Enum Attribute from current value if both cases above fails
}
```
---
### Author:  [@spiff](https://forum.aousd.org/u/spiff)
#### Post date: [September 28, 2024, 12:09am UTC](https://forum.aousd.org/t/question-regarding-allowedtokens/1857/4 "2024-09-28T00:09:25Z")
SchemRegistry Prim/Property definitions will only contain metadata fallbacks that were defined as part of the schema in the `schema.usda` source file - **not** anything authored in a particular scene.
Querying the UsdProperty directly will always consult both sources - you just won’t be able to tell which one it came from unless you consult the UsdPropertyStack for the property, or additionionally using your first batch of code.