What's the difinion of EFI_PEI_SERVICES?
typedef EFI_PEI_SERVICES {
  EFI_TABLE_HEADER                     Hdr;
  //
  // PPI Functions
  //
  EFI_PEI_INSTALL_PPI                 InstallPpi;
  EFI_PEI_REINSTALL_PPI               ReInstallPpi;
  EFI_PEI_LOCATE_PPI                  LocatePpi;
  EFI_PEI_NOTIFY_PPI                  NotifyPpi;

  //
  // Boot Mode Functions
  //
  EFI_PEI_GET_BOOT_MODE               GetBootMode;
  EFI_PEI_SET_BOOT_MODE               SetBootMode;

  //
  // HOB Functions
  //
  EFI_PEI_GET_HOB_LIST                GetHobList;
  EFI_PEI_CREATE_HOB                  CreateHob;

  //
  // Firmware Volume Functions
  //
  EFI_PEI_FFS_FIND_NEXT_VOLUME2       FfsFindNextVolume;
  EFI_PEI_FFS_FIND_NEXT_FILE2         FfsFindNextFile;
  EFI_PEI_FFS_FIND_SECTION_DATA2      FfsFindSectionData;

  //
  // PEI Memory Functions
  //
  EFI_PEI_INSTALL_PEI_MEMORY          InstallPeiMemory;
  EFI_PEI_ALLOCATE_PAGES              AllocatePages;
  EFI_PEI_ALLOCATE_POOL               AllocatePool;
  EFI_PEI_COPY_MEM                    CopyMem;
  EFI_PEI_SET_MEM                     SetMem;

  //
  // Status Code
  EFI_PEI_REPORT_STATUS_CODE          ReportStatusCode;

  //
  // Reset
  //
  EFI_PEI_RESET_SYSTEM                ResetSystem;
  //
  // (the following interfaces are installed by publishing PEIM)
  //
  // I/O Abstractions
  //
  EFI_PEI_CPU_IO_PPI                  *CpuIo;
  EFI_PEI_PCI_CFG2_PPI                *PciCfg;

  //
  // Additional File System-Related Services
  //
  EFI_PEI_FFS_FIND_BY_NAME            FfsFindFileByName;
  EFI_PEI_FFS_GET_FILE_INFO           FfsGetFileInfo;
  EFI_PEI_FFS_GET_VOLUME_INFO         FfsGetVolumeInfo;
  EFI_PEI_REGISTER_FOR_SHADOW         RegisterForShadow;

  EFI_PEI_FFS_FIND_SECTION_DATA3      FindSectionData3;
  EFI_PEI_FFS_GET_FILE_INFO2          FfsGetFileInfo2;
  EFI_PEI_RESET2_SYSTEM               ResetSystem2;
  EFI_PEI_FREE_PAGES                  FreePages;
} EFI_PEI_SERVICES;
Below is an instruction that describes a task. Write a response that appropriately completes the request. ### Instruction: What's the difinion of EFI_PEI_SERVICES? ### Response: typedef EFI_PEI_SERVICES {
  EFI_TABLE_HEADER                     Hdr;
  //
  // PPI Functions
  //
  EFI_PEI_INSTALL_PPI                 InstallPpi;
  EFI_PEI_REINSTALL_PPI               ReInstallPpi;
  EFI_PEI_LOCATE_PPI                  LocatePpi;
  EFI_PEI_NOTIFY_PPI                  NotifyPpi;

  //
  // Boot Mode Functions
  //
  EFI_PEI_GET_BOOT_MODE               GetBootMode;
  EFI_PEI_SET_BOOT_MODE               SetBootMode;

  //
  // HOB Functions
  //
  EFI_PEI_GET_HOB_LIST                GetHobList;
  EFI_PEI_CREATE_HOB                  CreateHob;

  //
  // Firmware Volume Functions
  //
  EFI_PEI_FFS_FIND_NEXT_VOLUME2       FfsFindNextVolume;
  EFI_PEI_FFS_FIND_NEXT_FILE2         FfsFindNextFile;
  EFI_PEI_FFS_FIND_SECTION_DATA2      FfsFindSectionData;

  //
  // PEI Memory Functions
  //
  EFI_PEI_INSTALL_PEI_MEMORY          InstallPeiMemory;
  EFI_PEI_ALLOCATE_PAGES              AllocatePages;
  EFI_PEI_ALLOCATE_POOL               AllocatePool;
  EFI_PEI_COPY_MEM                    CopyMem;
  EFI_PEI_SET_MEM                     SetMem;

  //
  // Status Code
  EFI_PEI_REPORT_STATUS_CODE          ReportStatusCode;

  //
  // Reset
  //
  EFI_PEI_RESET_SYSTEM                ResetSystem;
  //
  // (the following interfaces are installed by publishing PEIM)
  //
  // I/O Abstractions
  //
  EFI_PEI_CPU_IO_PPI                  *CpuIo;
  EFI_PEI_PCI_CFG2_PPI                *PciCfg;

  //
  // Additional File System-Related Services
  //
  EFI_PEI_FFS_FIND_BY_NAME            FfsFindFileByName;
  EFI_PEI_FFS_GET_FILE_INFO           FfsGetFileInfo;
  EFI_PEI_FFS_GET_VOLUME_INFO         FfsGetVolumeInfo;
  EFI_PEI_REGISTER_FOR_SHADOW         RegisterForShadow;

  EFI_PEI_FFS_FIND_SECTION_DATA3      FindSectionData3;
  EFI_PEI_FFS_GET_FILE_INFO2          FfsGetFileInfo2;
  EFI_PEI_RESET2_SYSTEM               ResetSystem2;
  EFI_PEI_FREE_PAGES                  FreePages;
} EFI_PEI_SERVICES; 