List of toneme criteria
The Persistence Criterion
Criterion type: general

If a tone is contrastive and it persists in all contexts (i.e., it is not affected by tonal processes which could be regarded as criteria of tonemic status), such tone is considered to be a toneme.

The Extensibility Criterion
Criterion type: contour

If a tonal contour can be realized on a segmental unit (most often, word) represented by a sequence of TBUs, but can also be hosted by a segmental unit of the same level (e.g., a word) consisting of a single TBU, this tonal contour is a toneme.

The Non-Compositionality Criterion
Criterion type: contour

If a language has a tonal contour realized on one TBU composed of levels which are not available in this language as tonemes, this contour is a toneme.

The Shared TBU Criterion
Criterion type: general

If two level tones can be assigned to one TBU, both tones are tonemes (unless this contour is a toneme, see creteria for the contour tonemes above) , and neither is Ø.