Hello, I am working with Illumina's Global Screening Array in Iscan system. After extracting my data to plink format, I would like to convert Illumina's IDs to rsid with file provided by Illumina (https://support.illumina.com/content/dam/illumina-support/documents/downloads/productfiles/global-screening-array-24/v3-0/infinium-global-screening-array-24-v3-0-a1-b151-rsids.zip). However, I found 11139 "." in this file instead of rsid. Why there are so many dots? Are they informative or just trash?