Sometimes you may not want to type out the full answer as it is written on the card, so if lenient validation is enabled, these cases will not be marked as errors when checking the answer. Instead, they will just be shown in gray. Lenient validation is enabled by default, but it can be disabled or customized in the Anki add-on config page.
Since spaces, periods, and hyphens usually aren't important when checking answers, lenient validation will not show the answer as incorrect when they are missing. In the Anki add-on config page, you can customize which characters are allowed to be missing like this.
For example, if you type "We cooperated" for We co-operated., it shows:
Often, there are some words which are not required in an answer, such as text
in square brackets [...] or parentheses (...). When lenient validation is
enabled, this text is optional and will not be shown as incorrect if it is
missing. If it is included, the brackets or parentheses are optional as well.
For example, if you type "start" for start(ing), it shows:
And if you type "starting" for start(ing), it shows:
Sometimes there may be multiple similar words in an answer which are all
correct. If you separate these words with slashes (/), lenient validation
will accept any one of them, and will not mark the missing alternatives as
incorrect.
For example, if you type "set in my ways" for set in one's/my ways, it shows:
Spaces are only allowed in alternatives if the entire set of alternatives is
surrounded by square brackets [...] or parentheses (...), but note that
this also makes it optional. For example, if have a card with
we've got [a lot of/plenty of] time, you can type "we've got a lot of time":
But you could also type just "we've got time":
