extract-reading-order-ambiguous

All codes

• Type: warning
• Kind: unsupported (valid input that Lamina PDF doesn’t implement)

What happened

A page mixes horizontal and vertical writing. Extraction put its blocks in an order, but no layout rule tells which comes first, so the order is a guess.

Why

Japanese and Chinese pages often set the body vertically and captions, headings or page numbers horizontally. Without a structure tree, nothing in the file says how the two relate.

How to fix

Nothing to do in Lamina PDF; the file is valid. Like every warning, it fails the call in strict mode. Check the order of that page’s blocks, or ask for the order the content stream draws (ReadingOrder::ContentStream). A tagged file avoids the guess.

Example

A page whose body text is drawn with a vertical font (Identity-V) and whose page number is drawn with a horizontal one.

Data fields

None.

The location has the page’s pageIndex.