[Doitsu]

Originally Posted by Trane

EDIT: Having removed all blank sections, then CTRL+S and scrolling through the entire book again, now it's partial to inserting blank lines after the ordered lists. (This is a how-too book.) There are three ordered lists that follow each other with a few words at the start of each list (describing the list). When I SAVE, Sigil injects a few blank lines after each </ol> tag.

Usually, Sigil will insert at most one blank line. However, the cleanup code might insert additional lines, if your book contains invisible Unicode characters (e.g. &#8203; or &#65279;) that some book distributors insert as part of a social watermarking scheme.
If you're cleaning up a commercial ebook that is protected by a social watermarking scheme, it might contain several of these invisible characters, which you can find with DiapDealer's Shady Characters plugin.

The following customized ShadyCharacters.json file will help you find many commonly used invisible characters:

Spoiler:

{
  "matrix": {
    "zwnj": [
      "0x200C", 
      "‌"
    ], 
    "zwj": [
      "0x200D", 
      "‍"
    ], 
    "shy": [
      "0x00AD", 
      "­"
    ], 
    "zwnbsp": [
      "0xFEFF", 
      ""
    ], 
    "wj": [
      "0x2060", 
      "⁠"
    ], 
    "nbsp": [
      "0x00A0", 
      " "
    ], 
    "thinsp": [
      "0x2009", 
      " "
    ], 
    "zwsp": [
      "0x200B", 
      "​"
    ], 
    "nnbsp": [
      "0x202F", 
      " "
    ]
  }
}

For more information on where to find this file, see the Shady Characters MR topic.