Coding-Decoding

At a glance 10 rules

1. 1Letter positions: EJOTYE, J, O, T, Y are 5, 10, 15, 20, 25. Count one or two steps from the nearest anchor to get any letter's position fast (R is 18, K is 11).
2. 2Check the shift twiceRead the shift off the first letter and confirm it on the last before you use it. Past Z the count wraps round to A.
3. 3Shifts that changeIf one shift does not fit, write the gap under each letter: it may alternate ($+2$, $-2$) or grow with the place ($+1$, $+2$, $+3$).
4. 4Mirror letters: sum 27A and Z, B and Y, M and N: a letter and its mirror add up to 27, so the mirror of the nth letter is the $(27 - n)$th.
5. 5Reversed, swapped or sortedIf the code holds the word's letters (or letters one step on) in a new order, test reversal, pair swaps and sorting. With place-based shifts, test which step comes first.
6. 6When examples disagreeIf two examples use different shifts, find what changed between the words: the number of letters, the number of vowels, or a letter's place.
7. 7Number codesTest in turn: each letter's position, position plus or minus a fixed number, the reverse value $27 - n$, then the sum of the positions, alone or times a fixed number.
8. 8Letter-to-digit codesLine each word up with its digits. A letter that appears in two words must get the same digit both times, which confirms the reading.
9. 9Sentence codesA word found in two sentences takes the one code they share. Strike out each solved pair and repeat until the word asked for stands alone.
10. 10Renamed objectsWhen things are renamed ('pen is called ink'), find the real object first, then answer with the name the code gives it.