A "space" or a "period" takes a bit to contain it. It been a few years but I believe 16 bits is used to contain a word, regardless of the number of characters in the word. If the word is just a single character, such as the as the article "a", it still requires the full 16 bits that defines a word.
Just like the number zero (0) is a holding is counted when you count the number of digits, a space is counted as a character. 90001 contains five digits, not two, even through the "0" only represents a place value.
It's been years since I worked with this so I am probably doing a bad job of explaining it.