A more thorough explanation:

The Rule in Wild's Case is a legal principle that applies to property grants. It states that if a grant is made to "A and A's children," and A's children do not exist at the time the grant takes effect, then the grant is considered a fee tail. However, if A's children do exist at the time the grant takes effect, then the grant is considered a joint tenancy.

For example, if a property is granted to John and his children, but John has no children at the time the grant takes effect, then John would have a fee tail in the property. However, if John has children at the time the grant takes effect, then he and his children would have a joint tenancy in the property.

It's important to note that the Rule in Wild's Case has been abolished in most states, along with the fee tail. This means that property grants are typically interpreted differently today, and the concept of a fee tail is no longer recognized in many jurisdictions.