The Workspace edit
Wikisource uses "namespaces" to separate different types of page. For example, the page you are reading now is in the "Help:" namespace.
Wikisource uses two namespaces for its page scans. These are the "Index:" namespace and the "Page:" namespace. Together, they are sometimes called the "Workspace". The workspace is the backroom where works are proofread from the scans. It is not supposed to be the place where readers will read the finished work (although they can if they want to). Finished works end up in the "Main" namespace (the only namespace that does not use a prefix like "Help:") through a process called "transclusion".
The Index namespace edit
This namespace holds "indexes" for all the works. Indexes are high level pages that:
- Link to all of the individual pages in the work
- Link back to the page scan files (in the "File:" namespace)
- List some simple metadata (such as title, author etc)
The Index can be modified to show the original page numbers and replicate the Table of Contents from the work (if available). For more information, see Help:Beginner's guide to Index: files and Help:Index pages.
All index pages are sorted in Category:Index.
A sample index can be found at Index:Cinderella (1865).djvu.
The Page namespace edit
This namespace is used to display individual page scans. On each page, the text is shown side-by-side with scanned image. This allows transcription of the original text. You can zoom in on the page image by clicking and scrolling on the image in the right-hand pane.
Page scan numbers are indicated in the pagename by a forward slash followed by a number after the file name. For example, Page:Sketch of Connecticut, Forty Years Since.djvu/27 displays the 27th page of the file. This number is the number of the page in the page scan file and not the page number in the book or any other type of work.
The text on the left can be modified in edit mode, only the contents of the edit box are displayed on the main namespace.
A sample page can be found at Page:Cinderella (1865).djvu/5.
Browsing edit
Depending on the skin that you are using, there will be either buttons or text labels appearing for navigating and editing the Page: namespace
previous page
next page
the Index for the page
show/hide the interface for editing the header and footer
vertical/horizontal layout
zoom out on scan
zoom in on scan
reset zoom
edit
Some text and formatting may be placed outside of the main "body" edit box. There are two other edit boxes, the "header" and "footer" edit boxes, that are not normally visible in edit mode. Any text typed into these edit boxes will only appear in the Page namespace. It will not be transcluded to the main namespace. This is used for things like page numbers which will make the text unreadable if they were included in the final product.
The header and footer edit boxes can be made visible clicking the 
button, which is in the "Proofread tools" toolbar, hovering in the upper left corner of the page image. Clicking the button again will hide the header and footer.
If you would like the header and footer to always be visible whenever you access the Page namespace, there is an option in you preferences. Select the "Editing" preferences and find the "Show header and footer fields when editing in the Page namespace" option under the list of advanced options. Make sure this option is ticked and save the changes. Once this option is saved, the header and footer will start visible by default; clicking the button will still toggle visibility on and off.
In technical terms, the header and footer are automatically placed inside <noinclude>...</noinclude> tags which prevent transclusion of their contents into any other page.
An example is Page:Cinderella (1865).djvu/5 which hides the title, repeated on every page, and the page number.
When editing, certain markup including table syntax must be balanced (equal numbers of opening and closing tags) across the combination of the Header, body and Footer, or self contained with in each section.
- See also: this discussion re: tricks for dealing with even and odd page numbers.
The main namespace edit
This namespace is not part of the workspace. It is sometimes also called the "mainspace". It is the final stage for proofreading: this is where readers are expected to find, access and read the text produced in the workspace.
The text is "transcluded" into the main namespace from the Page namespace. Usually a chapter or section is transcluded to a page in the mainspace, although sometimes an entire work can be transcluded to one page. Links floating at the left of the page link back to the Page namespace (these are usually page numbers, using information from the Index page). The "Source" link at the top of the page links back to the Index namespace.
Only the text in the "body" edit box from the Page namespace is transcluded into the main namespace. The text in the header and footer of the Page namespace is not translcuded.
A sample mainspace page can be found at Cinderella, or the Little Glass Slipper (Dalziel).