You've realized that you can make your knitting/crocheting instructions more concise and less confusing by inserting instructions for a repeat. But how? Is there accepted nomenclature that is universally recognized by knitters and crocheters? There are a number of acceptable methods to indicate a repeat within a row or round.
Asterisks, parentheses and/or brackets are the character symbols used for this purpose in pattern writing for both knitting and crocheting. Consider the following examples:
Row # (RS): (K3, p2) across.
Row # (RS): *K3, p2; rep from * to end of row.
Row # (RS): *K3, p2 ** rep from * to ** to end of row.
All three statements give the same results.
For crocheting, the same applies.
Row # (RS): Ch3, (dc in next dc, ch1) across to last st, 1dc.
Row # (RS): Ch3, *dc in next dc, ch1; rep from * to last st, 1dc.
Row # (RS): Ch3, *dc in next dc, ch1 ** rep from * to ** to last st, 1dc.
Again, all three statements result in the same sequence of stitches across the row. These are all acceptable methods for indicating a repeat.
What happens when you have a repeat within a repeat? How to express that? Now, you can use a combination of asterisks and parentheses.
Row # (RS): K3, *k2, (kfb, p1) 2 times; rep from * to last 5 sts, k5.
Row # (RS): Ch3, *dc in next st, (dc in next st, ch1, dc in same st) 2 times; rep from * to last 2 sts, 2dc.
There are some things to keep in mind when condensing instructions using repeat formatting.
Are all the stitches accounted for? Using the first knitting example (k3, p2), the stitch count across the row should be a multiple of 5. Had this row been worked over 21 stitches, instructions for how that final stitch should be worked needed to be included:
Row # (RS): *K3, p2; rep from * to last st, k1.
In this case, it would not be correct to ask the knitter to continue to k3, p2 across until they run out of stitches, ending with an incomplete repeat.
Have you included enough detail to make the instructions as easily digestible for the knitter/crocheter as possible? Telling them to repeat something 25 times may be pushing too far. Asking them to repeat a certain sequence of stitches 25 times until there are 5 stitches remaining and then say how those remaining 5 stitches should be worked will make those instructions so much easier to execute. The knitter/crocheter can continue doing the repeats (without counting the number of repeats) until there are 5 stitches left to work.
Ensure that when you are inserting instructions for a repeat into a row, that is clearly understandable for the knitter/crocheter and doesn't introduce ambiguity.