The meaning of some parameters of the table space pctfree initrans maxtrans storage when creating a table

create table X_SMALL_AREA 
( 
  idx_id NUMBER(20) not null,
   pss_idx_id NUMBER(20),
   update_log VARCHAR2(512),
   update_date DATE,
   constraint PK_PSS_LOG primary key (idx_id),
   constraint FK_PSS_LOG foreign key (pss_idx_id)
      references POFS_SERIAL_SYSTEM (idx_id)
) 
tablespace TBSL_SDDQ  --The table segment X_SMALL_AREA is placed in the tablespace TBSL_SDDQ
  pctfree 10  --The block reserves 10% of the space for updating the block data to use
  initrans 1 --The  number of initialized transaction slots
  maxtrans 255 --The  maximum number of transaction slots
  storage  - - Storage parameters
  ( 
    initial 64k  -- extents (extent) extend 64k at a time
    minextents 1  -- minimum number of extents
    maxextents unlimited  -- the maximum extent unlimited 
  );