Give the function f the attribute SubValuesHoldAll:

As a result, subvalue arguments are not evaluated prior to entering the (in this case nonexistent) function body:

Compare with a function g that has no attributes:

Give the function inout the attribute SubValuesHoldAll:

Define a function of two subvalue arguments that returns them wrapped in Hold as well as the first without wrapping:

The normal argument is evaluated prior to entering the function body, but the subvalue argument is evaluated inside the function:

Give f both the SubValuesHoldAll and HoldAll attributes:

Neither normal nor subvalue arguments are evaluated:

Compare with a function that only has the SubValuesHoldAll argument:

As well as one that only has the HoldAll attribute:

Use HoldAll and Unevaluated to suppress evaluation of symbols wherever it would occur:

Find the length of a symbol's name even if it has a value:

Use the SubValuesHoldAll attribute to build an operator form of EchoTiming:

A similar result to SubValuesHoldAll can be achieved by defining a function that returns a Function with the HoldAll attribute:

However, there is a performance penalty for defining the intermediate pure function:

Use Evaluate to force evaluation of a subvalue argument of a SubValuesHoldAll function:

Use Unevaluated to temporarily treat a function as if it had the attribute SubValuesHoldAll:

All Sequence objects that appear in subvalue arguments are still by default flattened:

Unevaluated wrappers are stripped prior to entering the function body:

And upvalues are associated with subvalue arguments still fire: