Start with the full proper name by which your organization conducts its business. Remove all the blanks. Remove truly extraneous components, if there are any. If it is excessively long, abbreviate by trimming the parts whose removal will result in the least loss of recognizability outside the sphere in which your organization is already well known. It is your responsibility to ensure that you have the right to use the name you have chosen.
Legal characters are letters, digits, and the hyphen.
You may mix upper and lower case, or use all upper or all lower case. Software will ignore case, and users can type in whatever case they like. You should capitalize your subdomain name as you wish it to appear in machine generated lists, such as the return address generated in your outgoing electronic mail. Hyphens may be used to separate words if necessary or consistent with normal references to the proper name of your organization. The GC domain registrar is the final authority on all matters relating to registration and subsequent use of your subdomain name.