Form field appearance rendering type.
"Custom" - use custom appearance. The custom appearance has some improvements over the web appearance,
for example you can specify background / border colors.
"Web" - use standard field appearance using platform-native styling. See https://developer.mozilla.org/en-US/docs/Web/CSS/appearance for details.
"Predefined" - use predefined appearance stream from PDF when available, if appearance stream is not available, custom appearance will be used.
Form field appearance rendering type. "Custom" - use custom appearance. The custom appearance has some improvements over the web appearance, for example you can specify background / border colors. "Web" - use standard field appearance using platform-native styling. See https://developer.mozilla.org/en-US/docs/Web/CSS/appearance for details. "Predefined" - use predefined appearance stream from PDF when available, if appearance stream is not available, custom appearance will be used.