I saw a new question on Reddit asking why many pages were shorter than expected when there was clearly enough room left on the screen for another line of text. Widows and orphans seemed the obvious cause to me, except that it was also claimed that this is new behavior, not seen previously. I did some checking and it appears that there is a change in progress regarding widow/orphan handling in KFX format (Enhanced Typesetting).
The Amazon Kindle Publishing Guidelines (version 2019.1) lists "widows" and "orphans" in section 16.3.2 "Ignored Attributes" within Appendix B: "Attributes and Tags Supported by Enhanced Typesetting". The latest versions of the Kindle Previewer and Kindle Create strip these out when converting to KPF format. And until recently they have not appeared in KFX format in any published books I have examined.
This has now changed. In the last couple of weeks I have come across several published books that include the KFX equivalent of widow and orphan properties. In my testing they only work in the latest versions of the Kindle for iOS and Android apps. They are currently ignored in Kindle devices and the PC/Mac apps.
The default widow/orphan behavior has also changed recently. Enhanced typesetting in older software renders books with the equivalent of widows:1 and orphans:1. This includes Kindle for PC 1.26 and Kindle firmware 5.9.6. Newer software renders with a default of widows:2 and orphans:2. This includes Kindle firmware 5.12.2 and the latest iOS and Android apps.
Hopefully the Publishing Guidelines and the publisher software (Create and Previewer) will be updated to reflect this change in the near future.
The Amazon Kindle Publishing Guidelines (version 2019.1) lists "widows" and "orphans" in section 16.3.2 "Ignored Attributes" within Appendix B: "Attributes and Tags Supported by Enhanced Typesetting". The latest versions of the Kindle Previewer and Kindle Create strip these out when converting to KPF format. And until recently they have not appeared in KFX format in any published books I have examined.
This has now changed. In the last couple of weeks I have come across several published books that include the KFX equivalent of widow and orphan properties. In my testing they only work in the latest versions of the Kindle for iOS and Android apps. They are currently ignored in Kindle devices and the PC/Mac apps.
The default widow/orphan behavior has also changed recently. Enhanced typesetting in older software renders books with the equivalent of widows:1 and orphans:1. This includes Kindle for PC 1.26 and Kindle firmware 5.9.6. Newer software renders with a default of widows:2 and orphans:2. This includes Kindle firmware 5.12.2 and the latest iOS and Android apps.
Hopefully the Publishing Guidelines and the publisher software (Create and Previewer) will be updated to reflect this change in the near future.