יו"ד is the letter of potential. It is a dot which can then turn into any letter. [That is why a יו"ד at the beginning of a word is future tense. It is potential but not here yet.]
A wonder: The word for ink is "דיו" which is the letter יו"ד backwards. Ink is ALSO potentially any letter!!!
According to the Zohar Hakadosh - "יו"ד" is חכמה which is raw undeveloped wisdom [the word חכמה has the letters כח מה which means that the מה, the "what it is", is בכח - in potential]. חכמה is gematria גלם. They are both raw, as of yet undeveloped.
די"ו is תבונה which is the development of the חכמה [and the יו"ד]. The ink develops the raw potential of the "יו"ד.
Then comes ידו [your hand which executes actions] which is דעת - the full actualization of the חכמה and תבונה.
עי' נוקב מרגליות עמ' 261
