In the FAQ section appear these words: "If you are upgrading from MediaWiki 1.5 or newer to 1.35". Is that a mistake? Is that like saying "The price increased from $1.50 to $1.35"?
Topic on Manual talk:Upgrading
Version numbers are not decimal numbers---major (before the decimal) and minor (after the decimal) numbers are ordered separately. Thus version 1.5 is much older than 1.35 since 5<35. See Release notes for version history.
You're right! I don't know why I didn't pick up on that in that particular sentence, when it hasn't been a problem for me in countless other sentences about software versions. Maybe it's the lack of a 0 before the 5, or maybe it's the difference between something as obvious as "from version 5 to version 35" and ... well, as you said, the appearance of decimal numbers.
Now you have me wondering whether people naming software tend to pick a set number of decimal digits and then not to exceed it—e.g., if a they start with 1.x.y, x and y will always be one digit each (so the span is just 0–9), but, if they start with 1.xx.yyy, then xx will always be two digits (so the span is 00–99, not 0–99) and yyy will always be three digits (so the span is 000–999, not 0–999).
In the end, this is why I prefer colons to points (which scream "decimal point"). With a colon, it's obvious to me that 2:9 comes after 2:1 and before 2:10.