laundry-mark

listen to the pronunciation of laundry-mark
الإنجليزية - الإنجليزية
Alternative spelling of laundry mark
An identifying marking, usually in coded form and handwritten in indelible ink on an inconspicuous area of a garment, widely used until the mid-20th century as an organizing aid by merchants who cleaned and pressed clothing

Some of the numbers I remember had become useless information until the computer age brought forth the frequent necessity of thinking up passwords. . . . hen at least one letter is required, I type in my army laundry mark, which is my last initial and the final four digits of my serial number.