Example permissions.yml (PEX)

users:
    yourusernamehere:
        group:
        - admin
    anotheruser:
        group:
        - mod
    anotheruserrr:
        group:
        - player
groups:
    default:
        prefix: '&8No.permiss&f'
        default: true
        permissions:
        - promotion.promote
        options:
            rank: '1000'
    player:
        default: false
        inheritance: null
        permissions:
        - modifyworld.*
        options:
            rank: '500'
    veteran:
        default: false
        prefix: '&1Veteran &f'
        inheritance:
        - player
        permissions:
        - modifyworld.*
        options:
            rank: '400'
            message-format: '&9Veteran &b%player: &f%message'
    collaborator:
        default: false
        prefix: '&6Col&2labo&3ra&dtor &e%player &f%message'
        inheritance:
        - player
        permissions:
        - modifyworld.*
        options:
            rank: '300'
            message-format: '&6Col&2labo&3ra&dtor &8%player: &f%message'
    vip:
        default: false
        prefix: '&eVIP'
        inheritance:
        - collaborator
        permissions: null
        options:
            rank: '250'
            message-format: '&eVIP &a%player: &f%message'
    mod:
        default: false
        prefix: '&1MOD &9%player &3'
        inheritance:
        - collaborator
        permissions:
        - modifyworld.*
        options:
            rank: '200'
            message-format: '&1Mod &b%player: &f%message'
    caretaker:
        default: false
        prefix: '&7Caretaker&f'
        inheritance:
        - player
        permissions:
        - nodehere.*
        options:
            rank: '150'
            message-format: '&7Care&7taker &e%player: %message'
    caretaker2:
        default: false
        prefix: '&aCaretaker'
        inheritance:
        - mod
        permissions:
        - nodesgohere.*
        options:
            rank: '150'
            message-format: '&aCare&2taker &e%player: %message'
    owner:
        default: false
        prefix: '&4Admin &c'
        inheritance:
        - mod
        permissions:
        - modifyworld.*
        - '*'
        options:
            rank: '1'
            message-format: '&4Admin &f%player: &c%message'