AH Formatter / XSL Formatter
Q&A

fo:wrapper is convenient when you want to specify inheritable properties. For example: If you want to set the same indent in the child blocks of the fo:block-container,

<fo:block-container>
  <fo:wrapper start-indent="..." end-indent="...">
    <xsl:apply-templates/>
  </fo:wrapper>
</fo:block-container>

It is because block-container itself is indented and child of block-container is also indented, if you specify "indent" to fo:block-container instead of fo:wrapper.

Also you can specify non-inheritable property to fo:wrapper, then the child is inherited from its parent.

If the property is not specified to fo:wrapper, it is equivalent to specify default value. Then it looks as if fo:wrapper inhibits the inheritance.

<fo:flow border-before-style="solid">
  <fo:wrapper>
    <fo:block border-before-style="inherit">
      The "inherit" value is none.

<fo:flow border-before-style="solid">
  <fo:wrapper border-before-style="inherit">
    <fo:block border-before-style="inherit">
      The "inherit" value is solid.