1<assertions> 2 <assertion id="1" tag="ref:XSH6:41953:41953 pt:XSI"> 3The sighold () function adds a signal sig to the signal mask of the calling process. 4 </assertion> 5 <assertion id="2" tag="ref:XSH6:41970:41971 pt:XSI"> 6sighold will return 0 upon successful completion. 7 </assertion> 8 <assertion id="3" tag="ref:XSH6:41973:41974 pt:XSI"> 9If the function is passed an illegal signal number, then errno will be set to [EINVAL], and sighold() will 10return -1. 11 </assertion> 12</assertions> 13