placeholder
n.a temporary name, number, or image used to show where something else will go later. You use it when you are not sure of the final details yet.
n.a temporary value or object used to represent a missing or unknown element in a design or data structure. Often used in software development, graphic design, or publishing to maintain layout integrity during the drafting phase.
“I used the word 'NAME' as a placeholder for the customer's actual name.”
“The designer added a gray square as a placeholder for the final logo until the client provided the high-resolution file.”
“In the initial stages of the database schema, the developers used a generic identifier as a placeholder to ensure the table structure remained consistent before integrating the actual user data.”
“Nowhere is that clearer than in the title track, where the word Graceland had initially been written down as a placeholder.”
From place + holder.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.