PPML

Key takeaways

PPML belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect PPML to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of PPML from memory before moving on to harder problems.

Reference excerpt

PPML (Personalized Print Markup Language) is an XML-based industry standard printer language for variable data printing defined by PODi. The industry-wide consortium of 13 companies was initially formed to create PPML, and now has more than 400 member companies.

Overview PPML is an open, inter-operable, device-independent standard first released in 2000 to enable the widespread use of personalized print applications. PPML is made to enable efficient production printing of variable data; rather than sending 300 copies of the same data with only a name changed, PPML is designed to allow all the data to be sent to the printer at once, allowing for much faster printing, as data does not need to be transferred to the printer for each copy. High-volume print jobs are getting more complex due to higher demands for the layout, content and personalization of documents. This is particularly true in the case of "image-swapping", where different images are selected and replaced on a record-by-record basis. At the same time pressure on the operators at the machines is increasing. A third development relates to the rise of XML, as a neutral basis for multi-channel communication of documents to fax, internet, e-mail, electronic archive and printer. Personalized Print Markup Language (PPML) is the print industry's answer to these developments. PPML strongly reduces the complexity of the print-job, especially when color, images and personalized elements are being used. The RIP (describing the contents of a page in a rasterized image) is a lot faster. The Printing On Demand Initiative (PODi) is responsible for the concept and development of this new PPML standard. This platform combines all major suppliers in this market, with the initial development completed by Adobe Systems, EFI, CreoScitex, Hewlett-Packard, Kodak Nexpress, Xerox, IBM, Lexmark, Océ, XMPie, PageFlex, Printable, QuarkXPress, Kodak GCG Inkjet Printing Systems, and Xeikon working together as members of PODI.

Reusable Content The traditional printer languages retrieve a page, examine what is on it and start to create rasterized images to tell the printer device what is where and how it should be put on paper. This is repeated for every single page. High-volume print jobs easily contain tens of thousands of pages that all have to be RIPped. RIPping can become a problem if one realizes that a page with a color photo and a logo can reach a size of as much as 20 MB in PostScript. This costs an exceptional amount of processing power and memory space and is the most important cause of print processes running aground. This is why rated engine speeds are often not met and machines may be RIPping all night to be able to produce at a reasonable speed during the day. This bottleneck in printing can be solved by specifying reusable content. Reusable content items are things that are used on many of the pages. Reusable content can be fonts (letter types), logos (in all sorts of formats), signatures (for policies), diagrams (research results), images (advertising) and the like. An object that is reusable is often called a resource. PPML was designed to make this reuse of resources explicit and allows the printer to know which resources are needed at a particular point in the job. This allows a resource to be rasterized once and used many times instead of being rasterized on every page on which it is used.

Resource Management Reuse of resources solves only part of the problem. Ensuring that all the required resources are available on the printer is another big problem. In PPML this problem is solved by allowing references to resources via URLs (uniform resource locator). Now the printer can retrieve the resource via the URL if it doesn't have that particular resource yet. This eliminates the need to send all the needed resources along with the print job. The printer will simply retrieve those resources that it needs on the fly. If it already has the resource in its cache it does need not retrieve the resource. This works in the same way as a browser that gains speed by loading (parts of) a webpage from its cache. Not including resources in a print job leads to the potential problem of version control. PPML solves this problem by allowing the producer of the print job to specify a checksum for each resource that is referenced. A checksum is a large number that is calculated from the contents of a resource. By comparing a given checksum against the checksum of the resource in the cache the printer can check that it has the correct version of the resource.

Multiple format resources The print industry already has many formats to describe images, fonts and pages. Instead of defining new PPML-specific formats for resources, the choice was made to allow any existing format to be used directly. Therefore, PPML only describes how existing resources are combined to create pages, documents and jobs. This description uses XML to avoid inventing yet another format. Although this approach makes PPML very easy to generate, it does complicate the task of the PPML RIP (a.k.a. consumer). Of course not all consumers will implement every possible resource format on this earth. To create compatibility the Graphics Arts Conformance subset was defined.

Graphics Art Conformance The Graphics Art Conformance level (PPML/GA) defines a level of PPML for increased interoperability. This conformance level requires a Graphics Art Conformant PPML consumer to support: PostScript, PDF, TIFF and JPEG resources, and to process these files in a standardized manner. A PPML producer that generates a PPML dataset that conforms to the Graphics Art Conformance level (PPML/GA) can then be printed using any Graphics Art Conforming consumer device. Conformance of a PPML/GA dataset can be validated with the CheckPPML tool (which also acts as a viewer).

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with PPML

Start with the simplest possible case. Write down what PPML claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to PPML before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about PPML ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of PPML

In research: PPML appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses PPML in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: PPML is common in secondary-school and first-year university syllabi. It links to neighbouring topics Markup languages, XML markup languages, so understanding it makes those chapters shorter.
In everyday life: Look for PPML outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study PPML in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what PPML means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain PPML out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is PPML in simple terms?

PPML (Personalized Print Markup Language) is an XML-based industry standard printer language for variable data printing defined by PODi. The industry-wide consortium of 13 companies was initially formed to create PPML, and now has more than 400 member companies.

Why does PPML matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study PPML?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on PPML.