I am not associated with McNeel. The information below is based on knowledge gained reading publicly available information and by using Rhino for Windows. Some details may differ in Rhino for Mac. Corrections and additions are encouraged.
Rhino template files can be confusing. Why does a template file change some settings but not others? What is special about a template file? How is the template file selected? How can a new template file be created?
A Rhino template file is simply a standard .3dm file stored in a special location. The file itself is has the same .3dm format as all other .3dm files, and can contain objects. Document Properties and Layer Properties are stored in all .3dm files including template files. Rhino Options are not stored in .3dm files.
What makes template files unique compared to other .3dm files is when a template file can be used when starting Rhino or starting a new model using
New the file will not be overwritten by Save or SaveAs (unless deliberate). This allows Rhino to have the Document Properties and Layer Properties and any objects of the template file without inadvertently changing the template file.
Settings in Rhino are divided into several including Rhino Options and Document Properties. Rhino Options are independent of .3dm files. Document properties are associated with .3dm files. The Document Properties can be viewed and changed by opening a panel using the
Document Properties commands, or by clicking on the File menu > Properties. Note that the panel opened by all of the these methods has Document Properties at the top and Rhino Options below.
When a .3dm file is saved the current Document Properties and Layer Properties are saved in the file in addition to geometry, etc. When a .3dm file is opened the Document Properties and Layer Properties are set to those saved in the file being opened.
The difference of template files from other files is the location where the template files are stored. That location can be changed in Rhino Options > Files. In addition a default template file can be designated.
When a Rhino is started Rhino opens the default template file if one has been designated. The Document Properties and Layer Properties are set to those in the file and any objects in the file are also opened. Otherwise Rhino opens with the “No template” Document Properties. Important - the “No template” Document Properties are built into Rhino and are not generally the same as the default template document properties.
New command is used the list of template files saved in the special location is presented to the user. The user can select a template file and Rhino opens that file from the selected template file. The Document Properties and Layer Properties are set to those in the file and any objects in the file are also opened. The user can also select to use the “No template” Document Properties. The user can also set the selected template file as the default template file.
When the user executes
Save As the first time after starting Rhino or using
New the default location to store the file is last location a file was saved at, not the location of the template files. (It is possible to deliberately save a file to the special location of template files.)
New template files can be created using the
SaveAsTemplateFile command. Set the Document Properties and Layer Properties as desired. Add any objects which are desired in the template file. Then