Considera's exporting features can be expanded by installing plugins. Considera plugins have the file extension ".conex". You can install plugins by placing them in ~/Library/Application Support/Considera/Export Plugins/ or /Library/Application Suppot/Considera/Export Plugins/. You can also double-click plugins and Consider will open and install them in your user Application Support folder. Plugins will be available the next time you launch Considera.
Considera comes with three export plugins built in. One is an HTML exporter that lets you export your data from RTF/RTFD or from the Markdown format. Another exports the document as plain text. The last plugin exports the document as a Word document. These plugins can be turned off by clicking on Considera in the Finder, selecting "Get Info" from the File menu (cmd-I) and opening the "Plug-in" section. From there, you can turn them off using check boxes. Change take effect the next time you launch Considera.
Considera's export format is simple and anyone with some experience in Cocoa can make one. Information regarding the format is available in a well-documented example plugin available here. The example plugin is very simple but contains all the information necessary to building a own plugin.