When Tisha B’av falls on Shabbos, the fast is postponed to the following day. On Shabbos there are no limitations to the amounts or types of food that may be eaten. Public displays of mourning are forbidden, but private forms of mourning are required. Washing the hands or face with hot water [heated before Shabbos] is forbidden. Likewise, it is also forbidden to wash the entire body with cold water. There is a machlokes as to whether it is permissible to toivel in a [cold] mikveh.
(סעיף יט, ס"ק לט; ביאורים ומוספים דרשו, 61)
Hilchos Tefillin 32 (page 96)
מסעיף כ עד אמצע סעיף כג אבל אם היא
Who is Responsible to Inspect the Parshios?
Repairing a Parsha that has an Extra Letter
Dipping the Pen into the Ink Before Writing Hashem’s Name
Who is responsible to repair the parshios?
The sofer must pay careful attention to the proper spelling of words and the formation of letters as handed down through the mesora. Improperly formed, missing or extra letters will disqualify the parsha. If such writing is used in tefillin, the wearer will lose out on the mitzva and recite daily berachoslevatalah. After completing the writing, the sofer must proofread it two or three times to ensure accuracy. A sofer may not release a parsha until he has inspected it properly. Nonetheless, it is prudent for the consumer to have the parsha rechecked by a professional and even have it checked by a computer.
(סעיף כ-כא וס"ק קא; ביאורים ומוספים דרשו, 150)
Repairing a parsha that has an extra letter
A parsha lacking even one letter is pasul and cannot be repaired. Inserting the missing letter is forbidden because of k’sidron. An extra letter or word can be removed to kasher the parsha if the erasure does not create a space equal to nine letters (see YD 275:2) in width. In some situations the space can be reduced by lengthening a preceding beis, chaf or similar letter. If the space can be reduced to less than three letters’ worth, this should be done.
(סעיף כג וס"ק קי)
Dipping the pen into the ink before writing Hashem’s name
The ink on a freshly dipped pen cannot be used for writing any letter of Hashem’s name. If the sofer realizes that he will soon be out of ink, he should stop one letter before Hashem’s name to dip his pen into the ink. If he already completed the word, he should check to see if any prior letters need additional ink or if a missing tag needs to be written, etc., in order to find another use for the first drip of ink. There are two reasons for this requirement: 1) too much ink in the nib can cause a deformity in the letters of Hashem’s name, and 2) the sofer must first be mekadesh the ink before using it on Hashem’s name.
(סעיף כב וס"ק קז; ביאורים ומוספים דרשו, 151)
Before commencing writing, the sofer must verbally declare his intention to write the sefer Torah, tefillin or mezuzahlishma. He should say "I am writing this for the sake of the holiness of sefer Torah [or tefillin or mezuzah]."
The sofer must have a special intention to be ‘mekadesh‘ Hashem’s name when writing it. Some explain that the sofer must bear in mind that he is writing Hashem’s name. Other poskim say that it means that he must intend to infuse kedusha into what he is writing.
Even one letter of stam that was not written lishma is pasul. This lishma must be verbalized; intention alone is not enough. Retracing the writing cannot make it lishma.
Filling in a space between the letters of a word
Possible mishaps with enlarging a letter after it has been written
Why repairing an invalid letter is not a concern of k’sidron