Buffer Internals

Buffers contain fields not directly accessible by the Lisp programmer. We describe them here, naming them by the names used in the C code. Many are accessible indirectly in Lisp programs via Lisp primitives.

name

The buffer name is a string that names the buffer. It is guaranteed to be unique. See section Buffer Names.

save_modified

This field contains the time when the buffer was last saved, as an integer. See section Buffer Modification.

modtime

This field contains the modification time of the visited file. It is set when the file is written or read. Every time the buffer is written to the file, this field is compared to the modification time of the file. See section Buffer Modification.

auto_save_modified

This field contains the time when the buffer was last auto-saved.

last_window_start

This field contains the window-start position in the buffer as of the last time the buffer was displayed in a window.

undo_list

This field points to the buffer's undo list. See section Undo.

syntax_table_v

This field contains the syntax table for the buffer. See section Syntax Tables.

downcase_table

This field contains the conversion table for converting text to lower case. See section The Case Table.

upcase_table

This field contains the conversion table for converting text to upper case. See section The Case Table.

case_canon_table

This field contains the conversion table for canonicalizing text for case-folding search. See section The Case Table.

case_eqv_table

This field contains the equivalence table for case-folding search. See section The Case Table.

display_table

This field contains the buffer's display table, or nil if it doesn't have one. See section Display Tables.

markers

This field contains the chain of all markers that currently point into the buffer. Deletion of text in the buffer, and motion of the buffer's gap, must check each of these markers and perhaps update it. See section Markers.

backed_up

This field is a flag that tells whether a backup file has been made for the visited file of this buffer.

mark

This field contains the mark for the buffer. The mark is a marker, hence it is also included on the list markers. See section The Mark.

mark_active

This field is non-nil if the buffer's mark is active.

local_var_alist

This field contains the association list describing the buffer-local variable bindings of this buffer, not including the built-in buffer-local bindings that have special slots in the buffer object. (Those slots are omitted from this table.) See section Buffer-Local Variables.

base_buffer

This field holds the buffer's base buffer (if it is an indirect buffer), or nil.

keymap

This field holds the buffer's local keymap. See section Keymaps.

overlay_center

This field holds the current overlay center position. See section Overlays.

overlays_before

This field holds a list of the overlays in this buffer that end at or before the current overlay center position. They are sorted in order of decreasing end position.

overlays_after

This field holds a list of the overlays in this buffer that end after the current overlay center position. They are sorted in order of increasing beginning position.

enable_multibyte_characters

This field holds the buffer's local value of enable-multibyte-characters---either t or nil.

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