Windows File and Folder "Attributes" A or C

Solution 1:

Prior to windows 8/10 the attributes were:

R = READONLY
H = HIDDEN
S = SYSTEM
A = ARCHIVE 
C = COMPRESSED
N = NOT INDEXED
L = Reparse Points
O = OFFLINE
P = Sparse File
I = Not content indexed
T = TEMPORARY
E = ENCRYPTED

You should pay special attention to the offline attribute because it may affect the behavior of your backup software. Files with the O attribute may be skipped entirely because the software may assume they are stored elsewhere.

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Consider these answers on SO and SF for additional information:

https://superuser.com/questions/1214542/what-do-new-windows-8-10-attributes-mean-no-scrub-file-x-integrity-v-pinn/1215034

https://superuser.com/questions/44812/windows-explorers-file-attribute-column-values

Solution 2:

A = archive bit is set
C = compressed

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Solution 3:

Another attribute is E for Encrypted.

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Solution 4:

When Windows 7 "Backup and Restore" creates a "system image," it puts it in a root-level folder named WindowsImageBackup, which has the "I" attribute. Windows 7's "help attrib" command says:

C:\>help attrib
Displays or changes file attributes.

ATTRIB [+R | -R] [+A | -A ] [+S | -S] [+H | -H] [+I | -I]
       [drive:][path][filename] [/S [/D] [/L]]

  +   Sets an attribute.
  -   Clears an attribute.
  R   Read-only file attribute.
  A   Archive file attribute.
  S   System file attribute.
  H   Hidden file attribute.
  I   Not content indexed file attribute.
  [drive:][path][filename]
      Specifies a file or files for attrib to process.
  /S  Processes matching files in the current folder
      and all subfolders.
  /D  Processes folders as well.
  /L  Work on the attributes of the Symbolic Link versus
      the target of the Symbolic Link