Dalat is the fourth letter of the Samaritan alphabet and carries the numeral value four. It writes a plain d. The name is the inherited Northwest Semitic one behind Hebrew dalet, and the gloss usually given for it, a door, is a modern reconstruction argued from the word rather than a meaning anyone recorded at the time the script was in use.
The letter matters out of proportion to its sound because of what happens when scribes confuse it. A great many textual variants in ancient manuscripts are explained by a copyist reading one letter as another that looked like it, and which letters are confusable depends entirely on the script the copy was made in. Letters that converge in one hand stay distinct in another. That means the Samaritan and the square Hebrew traditions do not make the same mistakes: a variant that is easy to account for as a slip of the pen in one script may need a different explanation in the other, and comparing the two is one of the standard tools for working out how a reading arose.
Outside the Semitic alphabets the sign became Greek delta and Latin D, keeping its sound and its fourth place in each of them. The triangular Greek form and the Samaritan form look nothing alike, but they descend from the same Phoenician sign, and the divergence measures the centuries rather than any change of purpose.
The character is encoded at U+0803.