Internal backend properties
     
accidental-grob (layout object)- Accidental for this note. 
 accidental-grobs (list)- Alist with (NOTENAME . GROBLIST) entries
 add-cauda (boolean)- does this flexa require an additional cauda on the left side? 
 add-join (boolean)- is this ligature head joined with the next one by a vertical line? 
 add-stem (boolean)- is this ligature head a virga and therefore needs an additional stem on the right side? 
 adjacent-hairpins (unknown)- List of directly neighboring hairpins
 all-elements (unknown)- list of all grobs in this line. Its
function is to protect objects from being garbage collected. 
 arpeggio (layout object)- pointer to arpeggio object. 
 ascendens (boolean)- is this neume of an ascending type? 
 auctum (boolean)- is this neume liquescentically augmented? 
 axis-group-parent-X (layout object)- Containing X axis group
 axis-group-parent-Y (layout object)- Containing Y axis group
 bars (unknown)- list of bar line pointers. 
 beam (layout object)- pointer to the beam, if applicable. 
 begin-of-line-visible (boolean)- Used for marking ChordNames that should only show changes. 
 bounded-by-me (unknown)- list of spanners that have this
column as start/begin point. Only columns that have grobs or act as
bounds are spaced. 
 bracket (layout object)- the bracket for a  number. 
 cached-pure-extents (vector)- Used by a VerticalAxisGroup to cache the Y-extents of different column ranges. 
 cause (any type)- Any kind of causation objects (i.e. music, or perhaps translator) that was the cause for this grob. 
 cavum (boolean)- is this neume outlined? 
 circled-tip (boolean)- Put a circle at start/end of hairpins (al/del niente)
 columns (unknown)- list of grobs, typically containing
paper-columns or note-column objects. 
 common-refpoint-of-elements (layout object)- Caches the common_refpoint_of_array of the elements grob-set
 conditional-elements (unknown)- Internal use only
 context-info (integer)- Within a ligature, the final glyph or shape of a head may be affected by the left and/or right neighbour head.  context-info holds for each head such information about the left and right neighbour, encoded as a bit mask. 
 delta-position (number)- vertical position difference
 deminutum (boolean)- is this neume deminished? 
 descendens (boolean)- is this neume of a descendent type? 
 details (list)- alist of parameters for detailed grob behavior.
     
more information on the allowed parameters can be found by inspecting
lily/slur-scoring.cc, lily/beam-quanting.cc, and
lily/tie-formatting-problem.cc.  Setting debug-tie-scoring,
debug-beam-scoring or debug-slur-scoring also provides
useful clues.
     
 direction-source (layout object)- in case side-relative-direction is
set, which grob to get the direction from . 
 dot (layout object)- reference to Dots object. 
 dots (unknown)- multiple Dots objects. 
 elements (unknown)- list of grobs, type depending on the Grob
where this is set in. 
 encompass-objects (unknown)- Objects that a slur should avoid
in addition to notes and stems. 
 figures (unknown)- Figured bass objects for continuation line. 
 flexa-height (dimension, in staff space)- height of a flexa shape in a ligature grob in staff_space. 
 flexa-width (dimension, in staff space)- width of a flexa shape in a ligature grob in staff_space. 
 font (font metric)- Cached font metric object
 glyph-name (string)- a name of character within font. 
 grace-spacing (layout object)- a run of grace notes. 
 head-width (dimension, in staff space)- width of this ligature head
 heads (unknown)- List of note heads. 
 ideal-distances (list)- (obj . (dist . strength)) pairs. 
 important-column-ranks (vector)- Cache of columns that contain items-worth-living. 
 inclinatum (boolean)- is this neume an inclinatum? 
 interfaces (list)- list of symbols indicating the interfaces supported by this object. Is initialized from the 
meta field. 
 items-worth-living (unknown)- A list of interesting items. If
empty in a particular staff, then that staff is erased. 
 join-heads (boolean)- Whether to join the note heads of an ambitus grob with a vertical line. 
 join-right-amount (number)
least-squares-dy (number)- ideal beam slope, without damping. 
 left-items (unknown)
left-neighbors (unknown)-  List of
spacing-wish grobs that are close to the current column.
     
The closest spacing-wishes determine the actual distances between the
columns.
     
 linea (boolean)- attach vertical lines to this neume? 
 meta (list)- Contains meta information. It is an alist with the
entries 
name and interfaces. 
 minimum-distances (list)- list of rods, that have the format (obj . dist). 
 note-columns (pair)- list of NoteColumn grobs. 
 note-head (layout object)- A single note head
 note-heads (unknown)- List of note head grobs
 oriscus (boolean)- is this neume an oriscus? 
 pedal-text (layout object)- Pointer to the text of a mixed-style piano pedal. 
 pes-or-flexa (boolean)- shall this neume be joined with the previous head? 
 positioning-done (boolean)- Used to signal that a positioning element
did its job. This ensures that a positioning is only done once. 
 prefix-set (number)- a bit mask that holds all Gregorian head prefixes, such as 
\virga or \quilisma
 primitive (integer)- Pointer to a ligature primitive, i.e. an item similar to a note head that is part of a ligature. 
 pure-Y-extent (pair of numbers)- The estimated height of a system
 pure-relevant-elements (unknown)- The subset of elements that are relevant for finding the pure-Y-extent. 
 quant-score (string)- Beam quanting score – can be stored for
debugging
 quantize-position (boolean)- If set, a vertical alignment is aligned to be within staff spaces. 
 quantized-positions (pair of numbers)- Beam positions after quanting. 
 quilisma (boolean)- is this neume a quilisma? 
 rest (layout object)- the staff symbol grob that we're in. 
 rest-collision (layout object)- rest collision that a rest is in. 
 rests (unknown)- A list of rest objects. 
 right-items (unknown)
right-neighbors (unknown)- see left-neighbors
 script-stencil (pair)- Pair (
type . arg), which
acts as an index for looking up a Stencil object. 
 separation-item (layout object)- A separation item. 
 shorten (dimension, in staff space)- The amount of space that a
stem. Internally used to distribute beam shortening over stems. 
 side-support-elements (unknown)- the support, a list of grobs. 
 slur (layout object)- A pointer to a slur object
 spaceable-staves (unknown)- Objects to be spaced during page layout. 
 spacing (layout object)- the spacing spanner governing this section. 
 spacing-wishes (unknown)- List of note spacing or staff spacing objects. 
 staff-symbol (layout object)- the staff symbol grob that we're in. 
 stem (layout object)- pointer to Stem object. 
 stem-info (pair)- caching of stem parameters
 stems (unknown)- list of stem objects, corresponding to the notes that the arpeggio has to be before. 
 stropha (boolean)- Is this neume a stropha? 
 tie (layout object)
tremolo-flag (layout object)- The tremolo object on a stem. 
 tuplet-number (layout object)- the number for a bracket. 
 tuplets (unknown)- list of smaller tuplet brackets
 use-breve-rest (boolean)- Use breve rests for measures longer
than a whole rest. 
 virga (boolean)- Is this neume a virga? 
 x-offset (dimension, in staff space)- Extra horizontal offset for ligature heads.