A template message (also called an HSM), can be of various types. A template is divided into four (4) sections, viz. a header (optional), a body, a footer (optional), and the buttons (optional).
Just like the text in a WhatsApp message can be decorated by enclosing it in * *, _ _, ~ ~, ``` ```, the template can be submitted along with these accordingly. The text can further be formatted by giving new_line_breaks, bullets, emojis as and when needed. More than two consecutive line breaks are not allowed. Footer and text header can not have line breaks.
A template takes anywhere between a few minutes to 48 hours to get approved or rejected. Try getting templates approved a little in advance, keeping the time into consideration. Refer this guide to get clarity on template content structure and variable notations.
The steps to submit a template are as follows -
First and foremost, a template once submitted can not be edited. The only workaround is to submit a new template with updated content and a new name. Furthermore, the content that is subject to change can be put as variables. These variables are blanks in the template that are filled dynamically when the template is used to send a message. This increases the template's re-usability. Do note that variables are allowed only in the body section (no limit to the number of variables) and in the dynamic CTA URL button (only one variable allowed).