[css-break] Is an inline-block monolithic or may-be? #1111

Recently I happened to be in a discussion whether the 4.1. Possible Break Points section in CSS Fragmentation Module defines an inline-block must be monolithic or may be monolithic. I could read both ways, clarification is appreciated.

There are two paragraphs that may be read differently.

First it says:

Some content is not fragmentable, for example ... or a single line of text content. Such content is considered monolithic

IIUC this paragraph doesn't define inline-block yet since inline-block is not text content, but I could read it differently, considering inline-block is abstracted as an object replacement character.

Then it says:

Since line boxes contain no possible break points, inline-block and inline-table boxes (and other inline-level display types that establish a new formatting context) may also be considered monolithic.

The last part clearly defines inline-block may be monolithic. However, this paragraph also says "line boxes contain no possible break points", I could read this as "inline-block appearing in a line box must not be broken." An inline-block cannot live outside of a line box, so this paragraph maybe self contradicting depends on how you read.

@fantasai could you help to clarify?

Note, from our brief testing, in case this helps:

• Gecko does not break an inline-block.
• Edge/Trident can break an inline-block, normally between line boxes in the inline-block.
• WebKit/Blink can break an inline-block at arbitrary points.