ngl describe any information (a concrete data, an idea, an action etc...) as a ngl:data It is the most generic type. In ngl we don't talk about types but concepts (ngl:data:concept), the difference is theorical and can be demonstrated like this

ngc:function sum
    ngc number <a>
    ngc number <b>
ngl:sum<4,4> // ok
ngl:sum<4,[four]> // ok
// pseudo code
function sum(number, number)
sum(4,4) // ok
sum(4,"four") // type system error

[4.1] Concept

[4.2] Concrete

[4.3] Shape

[4.4] Variable

[4.5] Type