File: groff.info,  Node: Safer Mode,  Next: Compatibility Mode,  Prev: Implementation_Differences.php">Implementation Differences,  Up: Implementation_Differences.php">Implementation Differences

5.38.1 Safer Mode
-----------------

The formatter operates in "safer" mode by default; to mitigate risks
from untrusted input documents, the 'pi' and 'sy' requests are disabled.
GNU 'troff''s '-U' option enables "unsafe mode", restoring their
function and enabling additional 'groff' extension requests, 'open',
'opena', and 'pso'.  *Note I/O::.