Wildcards are placeholders in the prompt text that are replaced with a random value from a list of choices which allows for more variety in the prompts generated.

• SD.Next supports standard file-based wildcards in prompts.
• Wildcard support is enabled by default, can be disabled in settings -> extra networks if you want to use 3rd party extension instead of SD.Next built-in support.
• Wildcards folder is set in settings -> system paths, default is models\wildcards

TL;DR: string "__abc__" in prompt is matched to a file abc.txt inside wildcards folder

The prompt syntax for wildcards is:

a woman wearing a __color__ dress

In the wildcards folder, create file color.txt and add multiple choices with one choice per line:

red
green
blue

In addition to standard wildcards, SD.Next also supports curly braces syntax for inline choices:

woman with {blonde|brunette|red-head|purple highlights} hair

You can also mix and match both wildcards and curly braces in the same prompt:

woman with {blonde|__color__} hair

• Wildcards can be used in both positive and negative prompts
• Prompt can have any number of wildcards

  a woman wearing a __color__ dress and a __shape__ hat

• Wildcards can be nested
  Line inside wildcard file can also have a wildcard referrring to another wildcard, etc.
• Supports filename-only and path-based wildcards with full subfolder support
  If wildcard is refered as __color__ then it will look for file color.txt in wildcards folder and any subfoldrer
  If wildcard is refered as __nsp/color__ then it will look for color.txt only in nsp folder inside wildcards folder
• Wildcards files can be in one-choice per line or multiple choices per line separated by | format

Wildcard matches and replacements will be logged in the standard log with debug level:

DEBUG Wildcards apply: wildcard="color" choice="Yellow" file="models/wildcards/my-variations/color.txt" choices=930