---
title: kCMBlockBufferPermitEmptyReferenceFlag
framework: coremedia
role: symbol
role_heading: Global Variable
path: coremedia/kcmblockbufferpermitemptyreferenceflag
---

# kCMBlockBufferPermitEmptyReferenceFlag

Passed to CMBlockBuffer and CMBlockBuffer to allow references into a CMBlockBuffer that may not yet be populated.

## Declaration

```swift
var kCMBlockBufferPermitEmptyReferenceFlag: CMBlockBufferFlags { get }
```

## See Also

### Constants

- [kCMBlockBufferAssureMemoryNowFlag](coremedia/kcmblockbufferassurememorynowflag.md)
- [kCMBlockBufferAlwaysCopyDataFlag](coremedia/kcmblockbufferalwayscopydataflag.md)
- [kCMBlockBufferDontOptimizeDepthFlag](coremedia/kcmblockbufferdontoptimizedepthflag.md)