The 'r' controlled vowel /aw/ is a phoneme. It can be represented by many different graphemes. Many of these have an r letter within this grapheme, but not exclusively
In the word sword, it is represented by the digraph or.
In the word, saw, it is represented by the digraph aw See, the same phoneme, but no R letter in the grapheme
In the word, explore, it is represented by the trigraph ore.
