[css-flexbox-1] Add definitions for outer main/cross size in terminology

[gitspeaks]

The specification frequently uses phrases like:

"outer hypothetical main size"
"outer hypothetical cross size"
"outer cross size"
"outer flex base size"

However, the current terminology defines "main size" and "cross-size" in terms of width or height.

In English writing mode (row direction), this results in an invalid phrases like:

"outer hypothetical main size"

is "resolved" as:

"outer hypothetical width"

when the intended meaning is actually:

the outer size along the inline axis, clamped.

To resolve this, I propose adding explicit definitions:

• Outer main size: The outer size in the main dimension.
• Outer cross size: The outer size in the cross dimension.

For the phrase "outer flex base size", given its limited occurrences, I recommend rephrasing it as:

"flex base size plus any padding, border, and margin length of the element in the main dimension"

[Loirooriol]

invalid phrases like: "outer hypothetical main size"

Doesn't seem invalid to me.

is "resolved" as: "outer hypothetical width"

"hypothetical main size" is a clearly defined term, why are you trying to replace parts of the term with a possible synonym?

I propose adding explicit definitions

I mean, not opposed, but seem unnecessary unless you are very nitpicky, and in that case these don't help either because they define "outer main size" and not "outer hypothetical main size".

[gitspeaks]

This issue specifically concerns the use of the term "outer" in phrases like:

• "outer hypothetical main size"
• "outer hypothetical cross size"
• "outer cross size"
• "outer flex base size"

The confusion is not with the phrase "hypothetical main/cross size", which indeed resolves correctly since "hypothetical" is about the min/max constraints applied to width/height. The problem arises when "outer" is combined with "cross size" / "hypothetical main size" / "flex base size" under the current definitions, as it creates a semantic conflict— read: "margin box size width", "margin box size flex base size" which doesn't make sense structurally.

I proposed defining "outer main size" and not "outer hypothetical main size" Since I find it intuitive how "hypothetical" would apply in context when "outer main size" is clearly defined.

That said, if clarity demands further precision, I would fully support including the following definitions:

• Outer hypothetical main size: The outer main size after applying min/max constraints to the main size.
• Outer hypothetical cross size: The outer cross size after applying min/max constraints to the cross size.