Did you have a look at https://www.freepascal.org/docs.var https://www.freepascal.org/docs.var and especially at the RTL https://www.freepascal.org/docs-html/cu

Did you have a look at https://www.freepascal.org/docs.var https://www.freepascal.org/docs.var and especially at the RTL https://www.freepascal.org/docs-html/current/rtl/index.html https://www.freepascal.org/docs-html/current/rtl/index.html and FCL https://www.freepascal.org/docs-html/current/fcl/index.html https://www.freepascal.org/docs-html/current/fcl/index.html documentation? I think the Free Pascal team has done a good job documenting nearly everything!