Flag

Flag is a command to set or clear flags on atom sets. A flag is just some atom-specific property. A flag is either on or off for a residue. Possible flags are:

Flag name	Value	Description	Notes
focus	0	Atoms of Interest (i.e. a ligand in an active site)	Reserved for molecular modeling. Affects sculpting.
free	1	Free Atoms (free to move subject to a force-field)
restrain	2	Restrained Atoms (typically harmonically constrained)
fix	3	Fixed Atoms (no movement allowed)
exclude	4	Atoms which should not be part of any simulation
study	5
	6	Protein (polymer.protein selector)	See auto_classify_atoms and auto_show_classified
	7	Nucleic acid (polymer.nucleic selector)
	8-15	Free for end users to manipulate
	16-23	Reserved for external GUIs and linked applications
exfoliate	24	Remove surface from atoms when surfacing (redundant with excluding those atoms from the selection in show surface, sele)	Affects surface (with surface_mode=0), dots (with trim_dots=on), get_area
ignore	25	Ignore atoms altogether when surfacing
no_smooth	26	Do not smooth atom position	Affects cartoon
	27	Polymer	See auto_classify_atoms and auto_show_classified See Selection Algebra "Chemical classes"
	28	Solvent
	29	Organic
	30	Inorganic
	31	Guide atom (e.g. CA in proteins)

Usage

flag flag, selection [, action [, quiet ]]

If the auto_indicate_flags setting is true, then PyMOL will automatically create a selection called "indicate" which contains all atoms with that flag after applying the command.

Arguments

• flag = int or str: Flag name or value
• selection = str: atom selection
• action = set|clear|reset: Note that "reset" will set the flag on the given selection, and clear it on all other atoms {default: reset}

Examples

CYS residue with flag "ignore" (left) and flag "exfoliate" (right)

fab AC

# Image on the left
flag ignore, resn CYS
show surface

# Image on the right
flag ignore, all, clear
flag exfoliate, resn CYS
rebuild surface

# in sculpting, ensure the newMethyl group just added doesn't move around
flag fix, newMethyl

# Introspect the flags bitmask
iterate all, print(hex(flags))

# Select atoms with "fix" flag
select fixedatoms, flag 3