A roster is any list of sites assembled for the purpose of sharing. We describe common mechanisms for assembling and managing rosters.
# Journal
A page can be designated as a roster and passed around a community by forking it from site to site.
New members join the roster by forking the designated page and then convincing all other participants to fork it back.
Viewing the roster page loads the viewer's neighborhood from the sites saved in the journal.
# Story
A page can be designated as a roster and filled by some authority with Reference plugins citing any appropriate page from each participant.
New members join the roster by convincing the authority to add a reference to their site on the designated page.
Viewing the authoritative roster page loads the viewer's neighborhood from the references saved in the story.
# Plugin
A page can contain one or more Roster plugins where the markup lists the domain names of sites in the community. See About Roster Plugin
New members join the roster by convincing the authority to add their site to the markup for the plugin. A site need not be operational to be included in this roster.
Viewing a Roster plugin does not immediately load the sites into the neighborhood without some further user interaction.
Construct a Roster for sites within a farm. See Farm Roster Script
# Script
A roster can be kept in some non-wiki resource such as a spreadsheet maintained by an authority.
New members join the roster by some mechanism devised by the authority such as filling out an online form.
Viewing the spreadsheet, or some web page generated from the spreadsheet, does not immediately load the sites into the neighborhood.
However, the script author can create Lineup Links which will return the viewer to wiki with new pages loaded into the lineup and then consequently into the neighborhood. We offer one such script as an example. gist 
# Site
A roster can be kept in a site dedicated to the purpose owned by an authority where each page contains a consistent synopsis and a Reference to a representative page for a participant site.
New members join the roster by convincing the authority to add a page for their site.
Viewing any one page tells little about the roster. A search will find static keywords for possible participants which then requires selecting the site to add it to the viewer's neighborhood.