Annex D (normative) Compatibility features [depr]

D.14 char* streams [depr.str.strstreams]

D.14.2 Class strstreambuf [depr.strstreambuf]

D.14.2.4 strstreambuf overridden virtual functions [depr.strstreambuf.virtuals]

Table 153: seekoff positioning [tab:depr.strstreambuf.seekoff.pos]
Conditions
Result
(which & ios​::​in) != 0
positions the input sequence
(which & ios​::​out) != 0
positions the output sequence
(which & (ios​::​in | ios​::​out)) ==
(ios​::​in | ios​::​out) and either
way == ios​::​beg or way == ios​::​end
positions both the input and the output sequences
Otherwise
the positioning operation fails.