The .paged container
A .paged file is a valid IDML package with extra parts that the design map does not name, so InDesign opens it as ordinary IDML.
A .paged file is an IDML package with extra entries: rename it to .idml and InDesign opens it.
In short IDML readers find parts through the design map, and an entry the design map
does not name is ignored. That leaves room for a tool to store its own data inside a file
that stays valid IDML, the private-parts idiom EPUB and OpenDocument also allow. The
.paged file of the Paged editor is built this way: the full set of IDML parts, plus a
paged/ folder and a manifest.json that only Paged reads.
The layout
| Entry | What it is |
|---|---|
mimetype | The IDML media type, first and stored, exactly as in any IDML package |
META-INF/, designmap.xml, Resources/, MasterSpreads/, Spreads/, Stories/, XML/ | The IDML document, complete |
paged/<plugin>/… | Data that a plugin keeps with the document |
paged/core/… | Paged's own parts, such as its document model |
manifest.json | An index of the paged/ entries |
Nothing in the design map refers to paged/ or manifest.json, so any IDML reader sees an
ordinary package. The file keeps the IDML media type rather than inventing its own: a reader
that checks the mimetype entry accepts it, and Paged recognises its own files by the
extra entries instead.
What a reader should expect
- Read it as IDML. Every rule in this section applies to the IDML half unchanged.
- Expect the extras to be invisible. InDesign ignores them on open. A tool that rewrites the package from its parsed content will not keep them unless it copies unknown entries through.
- Do not rely on the extras for content. The IDML parts describe the whole document on their own; the private parts are a convenience for the tool that wrote them.
In Paged: the model part
Parsed, not renderedpaged/core/model/document.pgmholds the document in Paged's own model, so a.pagedfile opens without an IDML import when that part is current; otherwise the IDML parts are read. A.pagedsave writes both, and an.idmlexport writes the IDML parts alone. See how Paged reads IDML.
Frequently asked questions
Can InDesign open a .paged file?
Yes, as IDML: the package carries every IDML part, the IDML media type and a design map that
names only IDML parts. InDesign ignores the extra entries.
Is this a different format from IDML? No. It is an IDML package with additional entries. The extra parts follow a convention other open package formats use: anything the manifest does not name is private.
Can I store my own data in an IDML package the same way? Yes, with the same caveat: other tools ignore your entries, and one that rebuilds the package from its parsed content will drop them. Keep everything the document needs in the IDML parts.
What InDesign needs to open a file
The rules a program writing IDML must follow for InDesign to open the file as intended — transforms, spread attributes, typed properties, part order.
Round-tripping & versions
What an IDML round trip keeps and recomputes, and how every package records the InDesign version and format revision that wrote it.