inventory:openInventory

This opens the own player inventory:

TriggerEvent('inventory:openInventory')

This opens a secondary inventory:

TriggerEvent('inventory:openInventory', {
    type = "stash", -- "type" in database
    id = "1", -- "identifier" in database
    title = "Chezza's Stash", 
    weight = 100, -- set to false for no weight,
    delay = 100,
    save = true -- save to database true or false
})