What characters should I use in the suffix of my DOI?

The easiest and recommended option is to use a randomly generated suffix. The auto-generated DOI strings use a-z and 0-9. They avoid i, l, o as they are easily mixed up with 0, 1. We group the suffix into blocks of 4, separated by a hyphen. You can generate a random suffix in both Fabrica and the API and your DOI will look something like this: 10.5438/9te8-5h68.

If you choose not to use this option, remember:

1. The DOI suffix must be unique within each prefix. The optimum length of a DOI suffix is 6–10 characters.

2. Only use a-z, 0-9 and - in a DOI suffix. Other characters might have special meaning or will be escaped. DOI suffixes are not case sensitive.

3. Avoid human-readable information in a DOI suffix because any meaning may change over time. Further advice on DOI suffixes.

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Reserved Characters

Reserved characters should not be included in a DOI suffix:
; | / | ? | : | @ | & | = | + | $ | ,

More resources:

DataCite blog post
Crossref blog post
Reserved characters in Elasticsearch
Technical implementation for generating random DOI strings

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Auto-generate a suffix

The auto-generate DOI name functionality means the DOI suffix is generated automatically and will look something like this: 10.15138/33bv-s284