What format or formats should you release it in? The choices have narrowed somewhat in the last year or two, but there’s still nothing approaching a “standard”. Here’s the lowdown on the current contenders.

Text (.txt)

Ah, the simple, universal and minimalist appeal of good old ASCII. This is the format to use if you want the widest possible distribution and acceptance. Anyone can read ASCII. Unix, Windows, Mac, Palm, Pocket PC, Rocket… Heck, even an old Commodore 64 can read ASCII. Project Gutenberg, a volunteer project to preserve the great public domain works of literature in digital form, uses ASCII because of it’s universal, cross platform nature. The downside, of course, is that you have to forgo fancy formatting like italics and aside from possibly distributing the book in a password-protected .zip file, you have no security. I’m not big on copy protection DRM, but I do think that the idea of ebooks at least being read-only has some appeal, so others can’t alter your work.

Open eBook/XHTML (.htm or .html)

A step beyond ASCII is Open eBook (OEB), itself a varient of XHTML (a dialect of XML that is nearly identical to HTML 4). Confused yet? This is still technically ASCII text, but marked up with XHTML tags and OEB metadata to convey more information about the book and more sophisticated formatting. OEB has the inside track to become the “standard” source format for ebooks, although few ebooks are actually distributed in raw OEB.

Microsoft Reader (.lit)

OEB “under the hood”, Microsoft’s Reader format is a compiled binary compressed ebook format that at the least protected publically available DRM, is “sealed” from user changes. Although it used OEB source files, you can’t read .lit files in a browser. You have to have a copy of Microsoft Reader to properly decompress and unencrypt them. Microsoft Reader files look great, and offer many of the advantages of paper books (pagination, highlighting, annotation) along with the advantages of ebooks (small file sizes, keyword searching, hyperlinks), but it’s not as “durable” a format as ASCII since you can only read it on platforms for which a version of Microsoft Reader is available.

Rich Text Format (.rtf)

If you were okay with the security limitations of ASCII but wanted a more sophisticated presentation, there’s always RTF. Readable on most modern GUI operating systems, RTF files are printable and offer varied formatting choices. They’re also useful as source files for other ebook options (like WordSmith on the PalmOS platform).

Adobe PDF (.pdf)

I hesitate to mention Adobe’s Portable Document Format as an ebook format, as that isn’t really what it was designed for. The vast thundering majority of PDF files out there are designed to be printed on letter-sized paper, and are very difficult to read on electronic screens. I’ve said before that PDF isn’t an ebook format so much as an electronic transmission and storage format for paper documents. Still, a lot of people insist on using PDF as an ebook format, so here it is. I will admit that for magazines, newsletters and other media for which layout is important, PDF probably provides the best preservation of the print layout.

And before I get into what I think of as the myriad of PDBs, a few words about the PalmOS platform and the difference between a file extension and file format.

PalmOS does not really understand the idea of files, and therefore doesn’t care about DOS/Windows file extentions. Everything inside a Palm device takes the form of a database, not a file. Therefore, all PalmOS databases appear on PCs as either .pdb (Palm Database) or .prc (Palm Resource Code) files. These extentions are stripped off and forgotten after the files have been transferred to a Palm, and you can’t tell anything about what kind of Palm databases they are from the DOS file extention. I generally try to make use of long filenames under Windows to give some clue to the actual database type (Between Heaven and Hell.isilo.pdb), but a lot of people don’t, so you really only have two ways to find out:

1. Transfer the file to your Palm and see if it shows up in your ebook reader.

2. Open the .pdb file in a PC text editor (be careful not to save it, as you could corrupt the file) and see if you can recognize the string of characters near the top of the file that defines the type of database you have. REAd is PalmDoc, togo is iSilo, BDOC is WordSmith, etc.

Now that we’re all sufficiently befuddled, the PalmOS formats:

PalmDoc (.pdb or .prc)

The original PalmOS ebook format, invented by Rick Bram for his Doc program, later bought out by Aportis to become AportisDoc. A PalmDoc (often referred to simply as Doc, but I’m trying to avoid confusion with Microsoft Word’s .doc format) file is, like everything else in a Palm, really a database. It takes the form of simple chain of 4k text records strung together. PalmDoc is the closest PalmOS format you’ll find to ASCII, in that does not support any real formatting and is relatively insecure (there’s lots of PalmDoc editors out there for PalmOS and Windows). That said, PalmDoc is probably the closest thing out there to a “universal” ebook format, in that it’s readable on even more modern platforms than ASCII.

Palm Reader (.pdb)

This is my favorite of the PalmOS formats, mostly because it allows sophisticated formatting, is at least read-only secured, and can be read on both PalmOS devices and Pocket PCs. This format is a marked up, encrypted variant of PalmDoc, and Palm Reader, the reader program for it from Palm Digital Media, can read PalmDoc files as well. This is also a good format to distribute in because it’s a fair bet that ebook reading folks will have the free Palm Reader program on their device already, since Palm Digital Media is one of the best (and cheapest) places to find legitimate current bestsellers in ebook format.

MobiPocket (.pdb)

MobiPocket is an up-and-coming format, largely due to their offering free readers for PalmOS and Pocket PC, and their partnership with Baen’s Webscriptions. MobiPocket’s format isn’t that hard to figure out; it’s standard PalmDoc with embedded HTML markup tags. You can read a MobiPocket ebook in any PalmDoc reader, but unless you like reading raw HTML, it won’t be comfortable. MobiPocket’s reader works pretty well, and the price is right. This is also probably the easiest PalmOS format to convert to if you’re starting with OEB source files.

iSilo (.pdb)

Another PalmOS format that starts with HTML is iSilo. iSilo isn’t a variant of PalmDoc, but uses its own proprietary encryption algorithm to achieve about 20% tighter compression that PalmDoc, Palm Reader or MobiPocket. It also supports pretty much all standard HTML formatting, including hyperlinks and tables. Because of the proprietary encryption, it’s a pretty secure format; converting to iSilo is a one-way proposition. No one has yet figured out how to decompile an iSilo document.

TomeRaider (.pdb)

TomeRaider is interesting because it’s, in true PalmOS style, as much database as ebook. While I’ve seen ebooks in TomeRaider format, it’s really better suited to reference works than prose, especially, record-based references like movie guides, travel guides, etc. The reader costs money, but is available for both the PalmOS and Pocket PC platforms.

In closing, it’s obvious that the “best” format in which to release your ebook is several of the above, as many as you feel you can support. Baen Books offers their webscriptions in RTF, .lit, MobiPocket, HTML and Gemstar’s .rb format (which I didn’t mention since it’s limited to the relatively small market of those with Rocket eBook dedicated readers). I usually offer mine in ASCII, OEB, .
lit, PalmDoc, RTF and Palm Reader formats. Until the ebook industry settles on a standard (which probably will end up one of the PalmOS formats unless Microsoft ports Microsoft Reader to PalmOS, something they haven’t ruled out), ebook publishers will have to make books available in formats their customers want, however many that might be.