Sharing some naming conventions is a key point to make it possible for a team to efficiently collaborate. This rule allows to check that all package names match a provided regular expression.
With default regular expression ^[a-z]|[a-z]+[a-z0-9_]*[a-z0-9]+$:
package MyPackage is ... end;
With default regular expression ^[a-z]|[a-z]+[a-z0-9_]*[a-z0-9]+$:
package my_package is ... end;