Help Project (single file):

Save the current project in compressed, single-file format (HMXZ). This is the only format available in the Basic version of Help & Manual. Same contents as the uncompressed HMXP format, with all files saved in a compressed zip archive with the extension .hmxz.

Help Project (uncompressed XML):

Professional and Server versions only. Save the current project in uncompressed XML format (HMXP). Required for multi-user editing and linking to version control systems. You must save in an empty folder, although you can add other sub-folders yourself later. All the files are plain-text XML, including the main HMXP project file.

Skin XML file:

Professional and Server versions only. Save the current project as a skin. You can then apply the templates, styles, variables and layout it contains to other projects on publishing by selecting the skin file in the Publish dialog. See Transforming your output with skins for details.

Save as a Repository:

Professional and Server versions only. A repository is a special uncompressed HMXP project without a table of contents. Linking it to a project makes the styles and topics in the repository available in the project. This enables you to share a common set of styles between multiple projects and use the topics in the project as snippets, together with the styles they are defined with. See Working with Repositories for details.

Rescue copy:

Save a backup copy of the current project in compact, single-file HMXZ format. You can then continue working in the current version. Unlike Save As HMXZ, it will not switch you out of the current copy to the new copy. This is also useful when you are working in a project linked to a version control system because it creates a local backup without disconnecting you from the VCS database.