This is the platform dependent conversion specifier for scanning and printing values of type gint64 See also G_GINT16_FORMAT

Some platforms do not support scanning and printing 64-bit integers, even though the types are supported. On such platforms G_GINT64_FORMAT is not defined. Note that scanf() may not support 64-bit integers, even if G_GINT64_FORMAT is defined. Due to its weak error handling, scanf() is not recommended for parsing anyway; consider using g_ascii_strtoull() instead.

enum GINT64_FORMAT = "li";