Required 

Usage: required

Required With 

Usage: required_with

Examples:

// require the field if the Field1 is present:
Usage: required_with=Field1

// require the field if the Field1 **or** Field2 is present:
Usage: required_with=Field1 Field2

Required With All 

Usage: required_with_all

Example:

// require the field if the Field1 and Field2 is present:
Usage: required_with_all=Field1 Field2

Is Default 

Usage: isdefault

Length 

Usage: len=10