Here is a simple filet crochet lace edging pattern for the ends of a fair linen, or even the hem of an alb. Usually a number 13 steel hook is used with Size 30 mercerized crochet cotton thread, but a smaller or larger size can be substituted depending on how fine or heavy you want the finished product to look.
The I.H.S. pattern is an old one, and comes from a lovely little book put out by The Order of Saint Veronica, which was a Roman Catholic society which aided poor mission chapels by collecting money for linens and creating Veronica Boxes filled with beautiful homemade linens and vestments which were shipped out to needy missions. Saint Monica is traditionally considered the Patroness of married women.