The dtddecl entries are not actually used by psgml , but they will be used by the sgml parser stay tuned ! , and they indicate what sgml declaration should be used with the dtd that has the same formal public identifier Psgml实际上不使用dtddecl项,但是sgml解析器(仍在调整中)将使用这些项,并且这些项表明了sgml声明将使用具有相同正式公共标识的dtd 。