[css-flexbox-1 ] What the meaning of the “definite used”

[UnVuTWFu]

reference the newest CSS-FLEXBOX

If the item has a definite used flex basis, that’s the flex base size.

I don't understand the meaning of “definite used flex-basis”.Does it mean that the used value of flex-basis is absolutely value?It seems semantic repetition.

[tabatkins]

It means the 'flex-basis' property's "used value" is a "definite size" (with some extra conditions that cause a size to be 'definite' in flexboxes vs elsewhere).

[UnVuTWFu]

Thanks for reply,I spend more time on reading specification.Now I have some questions about "definite" and "used value"

Questions:

1. Is "absolute theoretical value" same as "definite"?
2. How transform computed value to used value？

example A in [CSS-CASCADE]

For example, a declaration of 'width: auto' can’t be resolved into a length without knowing the layout of the element’s ancestors, so the computed value is 'auto', while the used value is an absolute length, such as '100px'. [CSS2]

example B in [CSS-FLEXBOX]

For example, percentage values of 'flex-basis' are resolved against the flex item’s containing block (i.e. its flex container); and if that containing block’s size is indefinite, the used value for 'flex-basis' is 'content'.

Example A says absolutizing 'auto' computed value,but example B says not absolutizing 'content' computed value.We have “Computed Value” line of the property definition table to define how to compute the computed value.Is there a same thing to define how to get used value?