+ (fret-diagram-details ,list? "An alist of detailed grob
+properties for fret diagrams. Each alist entry consists of a
+@code{(@var{property} . @var{value})} pair. The properties which can
+be included in @code{fret-diagram-details} include the following:
+
+@itemize @bullet
+@item
+@code{barre-type} -- Type of barre indication used. Choices include
+@code{curved}, @code{straight}, and @code{none}. Default
+@code{curved}.
+@item
+@code{capo-thickness} -- Thickness of capo indicator, in multiples of
+fret-space. Default value@tie{}0.5.
+@item
+@code{dot-color} -- Color of dots. Options include @code{black} and
+@code{white}. Default @code{black}.
+@item
+@code{dot-label-font-mag} -- Magnification for font used to label fret
+dots. Default value@tie{}1.
+@item
+@code{dot-position} -- Location of dot in fret space. Default 0.6 for
+dots without labels, 0.95-@code{dot-radius} for dots with labels.
+@item
+@code{dot-radius} -- Radius of dots, in terms of fret spaces. Default
+value 0.425 for labeled dots, 0.25 for unlabeled dots.
+@item
+@code{finger-code} -- Code for the type of fingering indication used.
+Options include @code{none}, @code{in-dot}, and @code{below-string}.
+Default @code{none} for markup fret diagrams, @code{below-string} for
+@code{FretBoards} fret diagrams.
+@item
+@code{fret-count} -- The number of frets. Default@tie{}4.
+@item
+@code{fret-label-custom-format} -- The format string to be used label
+the lowest fret number, when @code{number-type} equals to
+@code{custom}. Default@tie{}\"~a\".
+@item
+@code{fret-label-font-mag} -- The magnification of the font used to
+label the lowest fret number. Default@tie{}0.5.
+@item
+@code{fret-label-vertical-offset} -- The offset of the fret label from
+the center of the fret in direction parallel to strings.
+Default@tie{}0.
+@item
+@code{label-dir} -- Side to which the fret label is attached.
+@code{-1}, @code{#LEFT}, or @code{#DOWN} for left or down; @code{1},
+@code{#RIGHT}, or @code{#UP} for right or up. Default @code{#RIGHT}.
+@item
+@code{mute-string} -- Character string to be used to indicate muted
+string. Default @code{\"x\"}.
+@item
+@code{number-type} -- Type of numbers to use in fret label. Choices
+include @code{roman-lower}, @code{roman-upper}, @code{arabic} and
+@code{custom}. In the later case, the format string is supplied by
+the @code{fret-label-custom-format} property.
+Default @code{roman-lower}.
+@item
+@code{open-string} -- Character string to be used to indicate open
+string. Default @code{\"o\"}.
+@item
+@code{orientation} -- Orientation of fret-diagram. Options include
+@code{normal}, @code{landscape}, and @code{opposing-landscape}.
+Default @code{normal}.
+@item
+@code{string-count} -- The number of strings. Default@tie{}6.
+@item
+@code{string-label-font-mag} -- The magnification of the font used to
+label fingerings at the string, rather than in the dot. Default value
+0.6 for @code{normal} orientation, 0.5 for @code{landscape} and
+@code{opposing-landscape}.
+@item
+@code{string-thickness-factor} -- Factor for changing thickness of
+each string in the fret diagram. Thickness of string @var{k} is given
+by @code{thickness}
+* (1+@code{string-thickness-factor})@tie{}^ (@var{k}-1).
+Default@tie{}0.
+@item
+@code{top-fret-thickness} -- The thickness of the top fret line, as a
+multiple of the standard thickness. Default value@tie{}3.
+@item
+@code{xo-font-magnification} -- Magnification used for mute and open
+string indicators. Default value@tie{}0.5.
+@item
+@code{xo-padding} -- Padding for open and mute indicators from top
+fret. Default value 0.25.
+@end itemize")