Question

what is meant by main documents when you are using mail merge

Answer 1

It helps me to learn when I understand the releation ship between code in programming, in CSS
.speciall { } in an external style sheet would indicate a class selector which would then be used in the corresponding linked html document .
Now moving on to Javascript I would like to understand the basic relationship between code for example

Answer 2

Mail merge is a process to create personalized letters and pre-addressed envelopes or mailing labels for mass mailings from a form letter. When the mail merge process is run, the word processing system creates an output document for each row in the database, using the fixed text exactly as it appears.