The features that need to be added to be a fully, completed, authentic Pro-Ana experience are the following. However, its' still worth reading about from an education standpoint what these other standard features were:

[Links]
Links to other Pro-Ana pages, either real or archived. This is different than a Web Ring. These were essential because finding Pro-Ana sites (even though they weren't banned) was very difficult pre-Google. Numerous Guest Book comments on Pro-Ana sites relate how difficult it would be for someone to find a Pro-Ana site (despite their being so many). Many old sites contain Guest Book comments about how it took an hour to find the site.

Finding a site and planting your mark on a Guest Book page was actually a big deal this early in the history of Pro-Ana.

In 2000 and 2001 the emergency of "Top 10" or "Top 100" pages became important. See "Voting" below.

[Cliques]
Some Links to pages were not considered mere links, but links to "Pro-Ana Cliques".

There was zero consistency in the Pro-Ana community as to what constituted a normal page versus a Pro-Ana Clique.

[Ana Thinspo GIFs]
These were usually 2 frame GIFs with flashing text of a tiny thinspo picture. Often just around 80x80 pixels. Some sites were merely gallery of these Thinspo GIFs with motivational quotes on them.

[Thinspo "Gallery"]
Obviously this needs to be added! This was long before any "Gallery" website systems were common. They are usually basic hand-written HTML pages with maybe 6 to 10 thinspo pictures per page. A site having 20 or 30 thinspo pics would have been considered a gold mine. This of course was before Google Images.

Jodie Kidd was one of the most popular subjects (as all the Millenials are asking "Who???") Kate Moss was and still remains a perennial favorite, even back in 1999. There was always Karen Carpenter. Calista Flockhart of the 1990s TV show "Ally McBeal" was also a big favorite. This was right BEFORE Mary Kate become popular thinspo by a year or so.

[Fan Fiction]
This was another staple of Pro-Ana sites, typically over-sexualized Buffy the Vampire Slayer or homo-erotic Angel (the Buffy spinoff) fan fiction. It was a thing...and it's not a stereotype, it was literally a thing hugely common.

[Bands]
A section with links to band pages, or lyrics with popular Pro-Ana songs, or otherwise was very common. Many of what would become "Pro-Ana" sites or even Pro-Recovery sites STARTED OFF AS LITERAL BAND FAN PAGES.

For example, Something-Fishy (recovery but somewhat Ana-friendly), and House of Sins (majorly Pro-Ana) both were band pages BEFORE they were ED pages and only after the ED content came to dominate was their original purpose eventual dropped.

The most common band for Pro-Ana sites circa 1999-2001 was definitely the band Silverchair.

Additional sections that need to be added (that don't need much explanation) are:

Ana Religion (of course -- although this didn't become a thing widely until 2001)
Ana books list
Ana movies list
Calorie charts
BMI charts
Poetry
A link to the site-owner's online Open Diary.

[Site Owners Bio / About Me]
This is where site owners would usually put in their real first and last name, stats, age, their date of birth, and their pictures.

[Pop-Up Disclaimers]
Whether this was a good faith attempt to shoo people away, or to flatly state how Pro-Ana a site was (getting banned was NOT at a concern until 2001) adding some randomly chosen AUTHENTIC period disclaimer popups definitely is a must.

[Thank You note to the hosting provider]
Seriously, this was a major thing. Most pages would literally have a thank you / shout out to the hosting provider, whether it was paid (rare) or most-commonly, a free provider.