From the Microsoft Article on ICACLS
The entries are users and groups specific to that file (DOMAIN\USER or GROUP), the permissions listed are as follows:
SIDs may be in either numerical or friendly name form. If you use a numerical form, affix the wildcard character * to the beginning
of the SID.
icacls preserves the canonical order of ACE (Access Control Entries) entries as:
- Explicit denials
- Explicit grants
- Inherited denials
- Inherited grants
Perm is a permission mask that can be specified in one of the following forms:
- A sequence of simple rights:
- F (full access)
- M (modify access)
- RX (read and execute access)
- R (read-only access)
- W (write-only access)
- A comma-separated list in parenthesis of specific rights:
- D (delete)
- RC (read control)
- WDAC (write DAC)
- WO (write owner)
- S (synchronize)
- AS (access system security)
- MA (maximum allowed)
- GR (generic read)
- GW (generic write)
- GE (generic execute)
- GA (generic all)
- RD (read data/list directory)
- WD (write data/add file)
- AD (append data/add subdirectory)
- REA (read extended attributes)
- WEA (write extended attributes)
- X (execute/traverse)
- DC (delete child)
- RA (read attributes)
- WA (write attributes)
Inheritance rights may precede either Perm form, and they are applied only to directories:
- (OI): object inherit
- (CI): container inherit
- (IO): inherit only
- (NP): do not propagate inherit
- (I): permission inherited from parent container
For files, the permission masks are more or less self-explanatory:
R means you can read the file,
X allows it to be executed (as a program), and so on.
For other kinds of objects, you will have to browse MSDN:
Inheritance rights in English:
(I) "Inherited": This ACE was inherited from the parent container.
(OI) "Object inherit": This ACE will be inherited by objects placed in this container.
(CI) "Container inherit": This ACE will be inherited by subcontainers placed in this container.
(IO) "Inherit only": This ACE will be inherited (see
CI), but does not apply to this object itself.
(NP) "Do not propagate": This ACE will be inherited by objects and subcontainers one level deep – it will not apply to things inside subcontainers.
For the file system, "container" means a folder and "object" means a file, but remember that ACLs can be set on many other kinds of objects, not all of which have a concept of "containers".